Hyundai and Kia Engine Knocking in 2026: $0 to $8,000, and the Recall That Decides

Hyundai and Kia have filed three Part 573 reports for the same rod bearing defect, and together they name 1,660,160 vehicles. NHTSA 15V-568 landed on 10 September 2015 and covered 470,000 Sonatas. NHTSA 17V-226 and NHTSA 17V-224 were both filed on 31 March 2017, covering 572,000 Hyundais and 618,160 Kias. Same family of machining defect every time: the Hyundai reports describe metal debris left in the crankshaft restricting oil to the bearings, and the Kia report adds uneven crankpin surface roughness.

This is the most heavily documented engine knock on the American road, which is precisely why owners get it wrong. The campaigns carve populations by build date rather than model year, and the engine line inside each report excludes cars the headline appears to include. A Sportage owner reads "2011-2013 Sportage" and books an appointment; the report covers 8,417 turbo cars.

By the end you will know which document, if any, names your VIN; what the knock sensor software does and does not fix; what the short block warranty extension actually said and when its clock runs out; and what owners report paying when nothing covers them. Claims marked 🟢 rest on a numbered document in the Sources block. Claims marked ⚪ are estimates, and each says where it came from.

I built PulsCar after a $380 "full diagnostic" in Phuket in 2025 led to roughly $6,000 over six months across several shops, and the sound never went away (the story is on the About page). Nobody in that chain wrote down a test result the next shop could use, which is the failure every item below is built to prevent.

Engine speed or road speed, and does a document name your VIN

Read the routes, not the whole thing. Everything sorts on two questions: does your knock track engine speed or road speed, and does a document name your VIN. Each route carries who it fits, what it costs, the catch, and the sentence to say at the counter.

One rule overrides everything: coverage is decided by a production window and a warranty clock, never by the model name on the trunk lid. Every report here defines its population by engine, plant and build dates, so two identical-looking 2013 Optimas can sit on opposite sides of a recall.

First: is this the Theta II knock, or something cheaper?

Three splits separate the expensive family from the cheap one, and all three are free.

Split 1 — engine speed or road speed. Sit still, in park or neutral, and rev gently to about 2,500 rpm. If the knock quickens with the engine while the car is not moving, it is inside the engine. If it appears only when the wheels turn, it is a driveline, brake or suspension noise and this is the wrong guide. The report is precise: a metallic, cyclic knocking noise "which increases in frequency as the engine rpm increases."

Split 2 — cold, warm or loaded. A rattle only under acceleration, uphill and at high throttle is pre-ignition ping — normally fuel, carbon or timing rather than hardware, and the parent knocking guide ranks all six causes. Bearing noise gets worse warm, not better.

Split 3 — top end or bottom end. A light, fast tick following valve timing sits at the top of the engine and is usually cheap; the ticking guide separates that family. Bearing knock is lower, heavier and slower.

And one instrument that beats all three. The oil pressure lamp. 17V-226 lists four warnings in its own order: knocking noise from engine, reduced power and/or hesitation, check engine lamp, oil pressure lamp. A knock with an oil pressure lamp is not a diagnostic puzzle. It is a tow.

The ten-minute protocol before you spend anything

1. Run the VIN through NHTSA's recall lookup. Write down every campaign, open and completed. The completed ones matter as much, because a past engine replacement changes which warranty you are arguing about.
2. Read the build date on the driver's door jamb sticker. A 2013 Sonata built in February 2012 and one built in June 2012 sit in different documents.
3. Check which engine it has. 17V-224 names 2.4 GDI and 2.0 T-GDI. A non-turbo 2.4 Sportage and a V6 Sorento are outside it.
4. Start it cold, record thirty seconds, then rev to 2,500 rpm in neutral. Cold start is where bearing noise is loudest, and the rev test decides whether you are in this guide at all.
5. Check the oil level, then pull codes. Low oil with no puddle means it is being burned, and P1326 means the software already decided something about your bottom end.
6. Get the dealer's service history for the VIN. Ask whether an engine or short block was ever replaced under campaign, and when.

Eight Hyundai-Kia knock situations, and which is yours

"Deep knock, faster as I rev it, 2011-2014 Sonata." → Route 1. Run the VIN today.

"Knock plus the oil pressure light." → Route 1, and do not drive it there.

"Check-engine light, reduced power, code P1326." → Route 2. The software caught it, which is not fixing it.

"Dealer did the knock sensor update and now the light is on." → Route 2. Usually the update at work, but a passed bearing test sends it to wiring, sensor or software.

"No knock, but it eats a quart between changes." → Route 3, the early lane and the cheapest place in this guide to stand.

"Engine was replaced under the recall and it knocks again." → Route 4: which warranty does the replacement carry?

"2.4 Sportage, or a V6 Sorento, and it knocks." → Route 5. Read the engine line in 17V-224 first.

"2015 or newer and it knocks." → Route 5. No production window here reaches your build date.

What actually determines a Hyundai-Kia knock number

Which document names your build date. Larger than mileage, larger than symptom severity. Inside a campaign the bottom end is a $0 line; outside it, owner reports put the same repair in four figures.

Whether the knock sensor update is on the VIN. It gates the settlement's short block benefit, and it is a yes-or-no fact a dealer can read in a minute.

Which engine is in it. 17V-224 covers 2.4 GDI and 2.0 T-GDI. That one line removes naturally aspirated Sportages and V6 Sorentos from a recall their model names appear to be in — the most common misread we see.

Which warranty document is the current one. 15V-568 raised the short block warranty "to 10 years/120,000 miles for both original and subsequent owners" in 2015, and Kia's 2017 bulletins did the same for Optima, Sorento and Sportage. Hyundai's 2020 settlement added a Limited Lifetime long-block warranty (22-EM-001H, January 2022), first tied to the KSDS update, and widened the 10-year term in April 2022. Know both documents.

Whether you have service records. Denials in owner complaints often turn on maintenance documentation rather than the defect: 151 knock complaints in our sample mention being denied, refused or declined.

Dealer versus independent. Campaign work must go to a franchised dealer. Outside coverage an independent can fit a used or remanufactured engine for a fraction of a dealer price — the comparison maps which jobs go where.

The Hyundai-Kia knock price ladder, from the bottom up

The Hyundai-Kia knock number, by what you drive

Two rows invert the guide. The 2.4 Sportage and the V6 Sorento are the vehicles most often booked in for a recall that never covered them. And every row here has a written warranty extension behind it in numbers — 15V-568 for the Sonata, Kia's WTY004, WTY007 and WTY008 for Optima, Sportage and Sorento, and Hyundai's 22-EM-001H over its own rows from 2022, with Kia's PI1802 and PI1803 lifetime letters over Kia's.

The five Hyundai-Kia knock routes

Route 1 · Knock that rises with revs, and a VIN inside a campaign

The tell. Deep, metallic, and the rate follows the tachometer. 15V-568 describes it in one sentence worth memorizing: "A worn connecting rod bearing will produce a metallic, cyclic knocking noise from the engine which increases in frequency as the engine rpm increases." Quiet at idle early on, unmistakable at 2,000 to 2,500 rpm, and it does not fade as the engine warms.

What it actually is. Metal left over from machining the crankshaft: "if the debris is not completely removed from the crankshaft's oil passages, it can be forced into the connecting rod oiling passages restricting oil flow to the bearings." Less oil means hotter bearings, and a worn bearing knocks. 17V-224 adds a cause its Hyundai counterpart omits: "the machining processes of the crankpins caused an uneven surface roughness."

The line where you stop driving it. 17V-224 states it plainly: "If the warnings are ignored and the vehicle is continued to be driven, the bearing may fail and the vehicle could stall while in motion." All three reports carry the same safety risk sentence: "An engine stall at higher speeds can increase the risk of a crash." A knock with the oil pressure lamp lit is where a tow becomes the cheap option.

The cheap cause that gets skipped. The VIN lookup, free and one minute long. Owners in our sample repeatedly describe paying for engine work first and finding the campaign afterwards. All three reports carry reimbursement plans, so a past bill is a question to ask, not a loss to accept.

Where this does not apply. Model year is not enough. A 2013 Sonata built before 21 March 2012 is outside 17V-226's window. A 2.4 Sportage is outside 17V-224, which names only the 2.0 T-GDI there, and a V6 Sorento is outside it too, because the Sorento entry names 2.4 liter GDI engines.

At the shop — say this: "Please check this VIN against 15V-568, 17V-226 and 17V-224, and tell me which one names my build date. If one applies, I want the engine inspection performed under the campaign and the result in writing either way."

Route 2 · The knock sensor software has been installed, and the light is on

The tell. A blinking check-engine light, revs held near 1,800-2,000 rpm, about 65 mph at most, and a scan returning P1326. In our 4,649 complaints, 152 name P1326 by number and 467 describe limp mode or reduced power.

What it actually is, in NHTSA's own words. The closing resume for Engineering Analysis EA21-003 describes it as "an engine control software modification known as Knock Sensor Detection Software (KSDS) which is intended to detect impending engine failure, alert the driver, and limit engine power (to lessen likelihood of engine failure)." Detect, alert, limit. Nothing in that sentence repairs a bearing. The same document notes that "KSDS is being installed under recalls and non-safety field actions," which is why some owners got a campaign letter and others never heard the term until a code appeared.

The cheap cause that gets skipped. Reading the code before accepting a diagnosis. P1326 starts the argument rather than ending it: the factory procedure tests bearings first, and any parts counter reads it free. Two misreadings recur in the complaints: treating the update as the repair, and treating a passed inspection as a clean bill. Our sample describes cars updated, tested, passed and failed later. A bearing test is a measurement taken on a day, not a warranty.

The recalls that carry it, by number. Hyundai 20V-746 and 21V-727 both say dealers will inspect the engine, replace it if bearing damage is found, and "install a software update containing a new Knock Sensor Detection System (KSDS)." Kia's 20V-750, a fire recall, adds the KSDS update for 2012-2013 Sorento, 2012-2015 Forte and Koup, 2011-2013 Optima Hybrid, 2014-2015 Soul and 2012 Sportage; 21V-844 for 2017-2018 Optima Hybrid and PHEV; 23V-877 for the 2011 Sorento. The Soul's own engine paperwork, including two later piston ring recalls with their own noise-sensing software, is in the Kia Soul guide.

Where this does not apply. A light without P1326 is a different problem, and reduced power has cheaper causes — the hesitation guide covers them.

At the shop — say this: "Is P1326 stored, and has the knock sensor detection software been applied to this VIN? If it has, I want the bearing inspection result and the date of the software campaign printed on the invoice."

A rod bearing knock and a heat shield rattle are four figures apart, and they are told apart by ear long before anyone opens an engine. Both are audible with the car parked, which is what a recording can carry. Film the engine running, parked, for thirty seconds and upload it with your email; about ten minutes later PulsCar's free report gives an Engine Health Score, a system-by-system read (engine core, bearings, intake, belts, exhaust), a likely cause with severity, an independent second AI opinion and a repair-cost estimate — or "inconclusive" if the clip can't support a verdict. It is a first opinion, not a verdict: the rev test in neutral is what puts the noise inside the engine, and the VIN against the three campaign numbers is what decides who pays. Free, no card, no subscription. The report arrives by email, so use the address you actually read. For the noises ranked by what they cost, start here.

Which Hyundai and Kia engines are actually covered for knocking, and which only look covered? Three Part 573 reports carry this defect, and each names a production window rather than a model year. Recall 15V-568 covers 470,000 model year 2011 and 2012 Sonatas built at Hyundai Motor Manufacturing Alabama between 11 December 2009 and 12 April 2012. Recall 17V-226 covers 572,000 vehicles: 2013-2014 Sonatas built from 21 March 2012 to 29 May 2014, and 2013-2014 Santa Fe Sports built from 28 June 2012 to 31 May 2014. Recall 17V-224 covers 618,160 Kias, split inside the report as 443,825 Optima, 165,918 Sorento with the 2.4 GDI engine, and 8,417 Sportage with the 2.0 turbo only. A naturally aspirated 2.4 Sportage sits outside it. A PulsCar recording is a first read on the noise; the build window decides who pays.

Route 3 · It uses oil, and there is no knock yet

The tell. The level drops between services with nothing on the driveway and no blue haze, often noticed only when a low-oil warning appears three thousand miles after a change. What matters is that low oil is the condition the recall reports describe as damaging: restricted flow raises bearing temperature, and temperature wears the bearing.

What it actually is. Two things share this symptom. Oil leaving through rings or valve seals is being burned; oil leaving through a gasket is being lost. The first is an engine-condition question, the second a repair with a price — the oil leak cost guide maps that side by location.

The cheap cause that gets skipped. Actually measuring. Most owners describe consumption as "a lot" or "some", which no dealer can act on. A number can be acted on.

Fix it yourself — the consumption test. Change the oil, note the odometer, mark the dipstick level on paper. Check on level ground, engine cold, every 500 miles, writing each reading down. At 1,000 miles you have a rate. The honest limit: it tells you how much and how fast, not from where. Rings, seals, a gasket and a turbo all give the same number, and separating them needs a leak-down test and a borescope.

At the shop — say this: "It uses about this much oil per thousand miles and here are my dated readings. Can we do a leak-down test and a borescope before anyone talks about an engine, and can I have the numbers on the invoice?"

What happens after a Hyundai or Kia engine is replaced under one of these recalls? Sometimes a second recall. Kia filed 18V-907 in December 2018 for 68,127 vehicles that had already received an engine under 17V-224, and its Part 573 report is blunt: "The remedy for the previous recall 17v224 may not have been properly performed in all cases by Kia dealers. In some cases, the high pressure fuel pipe may have been damaged, misaligned or improperly torqued during the engine replacement procedure, allowing fuel to leak." The stated risk is fire and the only warning listed is fuel smell. Hyundai filed the twin nine days later: 18V-934 reaches 2011-2014 Sonata and 2013-2014 Santa Fe Sport "previously repaired under recall numbers 15V-568 and 17V-226." A completed engine replacement is worth writing down, because later documents are addressed to exactly that group. PulsCar gives a first read on the noise; the VIN lookup reads the paperwork.

Route 4 · The engine was replaced, and the knock came back

The tell. The same noise at the same place on the tachometer, on an engine with a fraction of the miles. Our sample contains repeated accounts of a replacement failing again, including one 2011 Sonata whose first engine went at 70,000 miles and whose replacement went at 90,000.

What the documents actually say. 15V-568's remedy raises the short block warranty "to 10 years/120,000 miles for both original and subsequent owners" of the qualifying 2011 and 2012 Sonatas — a clock attached to the vehicle, which a part fitted in year eight does not restart. And 18V-907 exists because the replacement procedure itself went wrong often enough to need its own recall.

The cheap cause that gets skipped. Asking for the original repair order before the new argument starts. It names the campaign, the part, the date and, if anyone wrote it down, the warranty that came with the replacement. Without that page you are negotiating from memory against a database.

Where this does not apply. A swap done by an independent shop with a used engine is a contract with that shop, and the terms are whatever the invoice says.

At the shop — say this: "Here is the repair order for the engine fitted on this date. What warranty attached to that part in months and miles, has 18V-907 or 18V-934 been checked against this VIN, and does the settlement's Lifetime Warranty reach this car?"

Route 5 · Nothing names your VIN

Before you accept that nothing covers you, check the settlement, not just the recalls. Hyundai and Kia settled together in one agreement, and judgment was entered on 10 June 2021 in case No. 8:17-cv-00838-JLS-JDE (C.D. Cal.). The Final Approval Order states size and scope in one place: "There are 3,956,568 Class Vehicles. Class Vehicles include: all 2011-2018 and certain 2019 model year Hyundai Sonata vehicles; all 2013-2018 and certain 2019 Hyundai Santa Fe Sport vehicles; all 2014-2015, 2018, and certain 2019 Hyundai Tucson vehicles; all 2011-2018 and certain 2019 Kia Optima vehicles; all 2012-2018 and certain 2019 Kia Sorento vehicles; and all 2011-2018 and certain 2019 Kia Sportage vehicles, originally equipped with or replaced with a genuine Theta II 2.0 liter or 2.4 liter gasoline direct injection engine within OEM specifications." Six nameplates, and the 2019 cars only where built before the KSDS technology entered production.

What the benefit is, word for word. A "Lifetime Warranty," defined as "the extension of the existing Powertrain Warranty to cover the short block assembly, consisting of the engine block, crankshaft and bearings, connecting rods and bearings, and pistons, in those Class Vehicles owned by individual consumers that have completed the KSDS update." It "shall also apply to any damage caused to the long block assembly due to connecting rod bearing failure," and "shall otherwise endure irrespective of the Class Vehicle's mileage or duration of ownership."

Three conditions decide whether it reaches you. First, it transfers: "the Lifetime Warranty shall persist in its full duration regardless of any transfer in ownership or lease of a Class Vehicle." Second, it is for people rather than trade — it "shall not apply or be available to commercial entities such as used car dealers, franchisees, or automobile auction houses." Third, and least reported: at "150,000 miles and more than eight (8) years from the original in-service date," the maker may instead, at the owner's election, "pay the owner $2,000.00 in lieu of an engine replacement" — and taking it requires the owner "to assume all risk going forward and to void the vehicle's remaining Lifetime Warranty." Both thresholds have to be crossed first.

The cheap cause that gets skipped. Reading the settlement before assuming nothing applies, and knowing the factory terms underneath it. NHTSA's audit query AQ25-001 records Kia's own statement of those terms: "the 10-year / 100,000-mile Powertrain warranty for original purchasers and a 5-year / 60,000-mile Limited Basic Warranty for subsequent purchasers." Two different coverages, decided by who bought the car new.

Fix it yourself — the decision, not the engine. Write down three numbers before authorizing anything: the lowest quote for a used engine with a written warranty, the dealer price, and what the car is worth running. One complaint in our sample records local shops "quoting $10,000 to rebuild or $12,000 for a new engine" in a single conversation. The honest limit: gathering the numbers is yours; the swap is not driveway work, and a used engine with no warranty is a second bet on the same defect family.

Where this does not apply. If the knock does not climb with the tachometer, go back to the first filter — the parent knocking guide covers the cheap causes. Plenty of expensive engine estimates start life as a heat shield.

At the shop — say this: "Has the KSDS update been completed on this VIN, and is this car a class vehicle under the Theta engine settlement? If yes, I want the short block assessed under the Lifetime Warranty. If no, quote me used, remanufactured and new separately, with the warranty terms beside each price."

How do you tell a covered Hyundai or Kia knock from an expensive guess? Two free steps settle it before anyone lifts the car. First, rev to about 2,500 rpm in neutral: if the knock rate follows the tachometer while the car is stationary, it is inside the engine, and 15V-568 describes exactly that as "a metallic, cyclic knocking noise from the engine which increases in frequency as the engine rpm increases." Second, run the VIN against 15V-568, 17V-226 and 17V-224 and read the production dates rather than the model year, because each report defines its population by build window and by engine. Recall 17V-224 alone splits into 443,825 Optima, 165,918 Sorento and 8,417 turbo Sportage. Then check whether the KSDS update is on the VIN, because the settlement's Lifetime Warranty is conditioned on it. A thirty-second PulsCar recording is a first read on the noise family, not a verdict.

What 4,649 NHTSA complaints about these six nameplates show

Everything above this line comes from recall reports, a settlement and a court docket. This section comes from the file underneath all of them: the complaints Americans filed with the federal government, narratives included, which we read ourselves rather than summarized from someone else's chart.

We loaded all 777,040 complaints received between 1 January 2015 and 8 September 2026 and kept the six nameplates the settlement names as Class Vehicles — Sonata, Santa Fe Sport, Tucson, Optima, Sorento and Sportage — in model years 2011 through 2019. That universe is 29,981 complaints. Inside it we kept every narrative carrying a knock or engine-failure word, then required an engine word within ninety characters of the match, which takes 5,265 raw hits down to 4,649 complaints. Thirty random matches were read in full at each stage to measure the error: the loose query carried two clear mis-sorts (a knock heard over speed bumps, a knock "in the steering location"), the tightened one carried a single airbag complaint that mentioned a past engine failure in passing. One caution that decides whether a count like this is worth anything: complaint narratives are all capitals through 2020 and mixed case from 2021 on, so every query here is case-insensitive. A case-sensitive uppercase filter would have quietly thrown away most of the last five years. The method file lists every filter, exclusion and sample-reading result.

This is a failure that strands you, and sometimes burns. In the 4,649, 12.54% report the vehicle was towed and 2.99% report a fire, against 5.11% and 1.82% across all 777,040 complaints. Crashes run the other way — 0.84% against 4.37% — the signature of a car that stops rather than one that collides. Thirty-four injuries appear and no deaths.

Half the file sits outside every production window on this page. Model years 2015 through 2019 account for 2,318 of the 4,649 (49.9%). No Part 573 report quoted above reaches a 2015 build date, which is exactly why the settlement and the warranty bulletins below matter more than the recall numbers for half the people reading this.

Mileage says the argument is about a clock, not a defect. 2,209 complaints carry a usable odometer figure: median 97,000 miles, quartiles 71,000 and 122,000. 26.0% are above 120,000 miles — the number that ends the 2017 written extensions — and 45.5% are above 100,000, the end of the original-owner powertrain warranty. A quarter of this file lies past the 120,000-mile caps of 2015-2022; only the lifetime and 15-year documents from 2018 on reach it.

And the file is still filling. Complaints in this set by year received: 448 in 2021, 589 in 2022, 534 in 2023, 490 in 2024, 576 in 2025, and 381 in the first eight months of 2026. Whatever else this is, it is not a closed historical episode with a tidy end date.

What the narratives say happened. A stall, shutdown or seizure appears in 2,149 (46.22%). A recall or campaign is named in 2,057 (44.25%). Denial language — denied, refused, declined, not covered, out of pocket — appears in 902 (19.40%). An engine or short block replacement is described in 851 (18.31%). And the two terms that decide coverage barely register: KSDS or the knock sensor detection system in 187 (4.02%), code P1326 in 152 (3.27%). That last pair is the finding to act on. The free software update is a stated condition of the biggest benefit available on these cars, and one owner in twenty-five mentions it at all. Download the subset counts.

What owners say the money was. From the same 4,649 we extracted every dollar figure between $500 and $30,000 sitting within eighty characters of both an engine word and a repair word, excluding windows that mention buying the car, a loan, trade-in value or a different component. That leaves 242 figures: median $6,700, quartiles $4,800 and $9,000, with 78.5% at or above $4,000 and Kia's 149 figures ($7,000) running above Hyundai's 93 ($6,000). Twenty read in context were genuine engine money, one was a wiring quote. This is a separate, larger extraction over a different date range than the 120 figures in the ladder above, and it lands in the same place — which is the most useful thing a second sample can do. It is still owner-typed text, not invoices. Download all 242 figures.

Which models and years fill the file

Counts are not failure rates. There is no denominator of cars on the road in this file, so nothing below says one nameplate is more or less reliable than another — Sonata sold in far larger numbers than Santa Fe Sport, and a bigger fleet files more complaints. What the table does show is where the knock reports concentrate and at what odometer reading they arrive.

The Tucson rows are the ones worth stopping on. Its 701 complaints peak at model year 2017 (197) and 2016 (119) — together 45.1% of all Tucson reports in the set — and those are precisely the two Tucson years that the Limited Lifetime Warranty bulletin below does not list. The 2017 cars have their own recall, 21V-727, covering 95,515 Tucsons and Sonata Hybrids for connecting rod bearing damage. The 2016 cars are not in that recall, but they are not uncovered. Hyundai bulletin 22-EM-006H-2, November 2022, extends coverage for connecting rod bearing wear to 15 years or 150,000 miles on "certain 2016-2021 MY Tucson (TL) vehicles with Nu 2.0L GDI engines," for original and subsequent owners. What no bulletin we found lists is the 1.6-liter turbo, and that is where the real gap for a 2016 Tucson sits. The settlement's Tucson entry names 2014-2015, 2018 and certain 2019 cars. Our Tucson guide quotes the 15-year bulletin in full.

Where the model-year peaks sit elsewhere. Sonata peaks at 2011 (270) and 2013 (246). Sorento peaks at 2016 (232) and 2015 (158) — both outside 17V-224's 2012-2014 window. Optima peaks at 2015 (223), again outside its recall. Sportage peaks at 2012 (153) and 2013 (143), inside the turbo-only window that covers 8,417 cars. Read as a shape rather than as a ranking, the file says the same thing twice: the recalls caught the front of this problem, and the reports kept coming from the years behind them. Per-model table · per model year.

The document most owners never see: a Limited Lifetime Warranty

The recalls are famous. The bulletin that replaced their warranty clock is not, and it is the single most valuable page in this guide for anyone whose VIN is not named by a campaign.

Hyundai TSB 22-EM-001H, January 2022, "Engine Warranty Extension (TXXI)." Opened as a PDF and read in full, it says: "The warranty coverage for engine long block repair or replacement regarding engine damage or malfunction from connecting rod bearing wear has been extended to a Limited Lifetime Warranty and is valid for original and subsequent owners." Long block, not short block. Lifetime, not ten years. And it transfers.

Which cars it lists, in its own words. Certain 2011-2014 Sonata (YF) and 2015-2019 Sonata (LF) with 2.0L Turbo and 2.4L engines; certain 2013-2018 Santa Fe Sport (AN); certain 2019 Santa Fe (TM); certain 2014-2015 Tucson (LM) and 2018-2019 Tucson (TL) with 2.4L engines. Compare that with the recall list at the top of this page: every Hyundai model year from 2015 to 2019 appears here and in no Part 573 report. The April 2022 revision, 22-EM-001H-1, repeats the list with "Theta II" spelled out beside each engine and supersedes the original.

The conditions, which are where claims are lost. The bulletin's own boxed notice limits the extension to vehicles owned by individual consumers that have "Completed the Knock Sensor Detection System software update (Campaign 953)" and show "a check engine warning lamp illumination with DTC P1326 (Campaign T3G)" or "an engine concern related to connecting rod bearing wear or damage." The superseding revision drops that box and adds two things to know: a Warranty Prior Approval must be submitted on every applicable vehicle, and the settlement background names the software update and the other exclusions — "certain vehicle neglect, vehicles previously deemed a total loss (i.e., branded or salvage), and ownership by certain commercial entities engaged in the business of leasing, buying, or selling used vehicles."

What this corrects on this page and everywhere else. The ten-year clock did not end the story. 15V-568's extension to 10 years/120,000 miles was the 2015 position; by 2022 the same failure could also carry a lifetime term for individual owners, gated, in the January 2022 text, on a free software appointment. Our sister guide reads the same bulletin against the Sonata specifically — Sonata problems by mileage — and the pages agree: the calendar is not what costs people this coverage. A missing Campaign 953 is what the notices flag.

Kia wrote its own extensions, and they are not the same document. In February and March 2017 Kia extended the New Vehicle Limited Warranty on the short block assembly — "engine block, crankshaft and bearings, connecting rods and bearings and pistons" — "to 10 years starting from the date of first service or 120,000 miles, whichever comes first, regardless of whether the vehicle owner is an original or subsequent vehicle owner," in three separate bulletins: WTY007 for 2011-2014 Sportage with the 2.0L Turbo GDI and 2.4L GDI, WTY008 for 2012-2014 Sorento with the 2.4L GDI, and WTY004 for all 2011-2014 Optima with the 2.4L GDI or 2.0L Turbo GDI, which states in the same breath that "Optima Hybrid vehicles are not included in this warranty extension." Each came with a reimbursement form for owners who had already paid "due to connecting rod failure." Two 2017 customer satisfaction bulletins extended the same terms to certain 2014 Optima and 2014 Sportage cars. What we got wrong the first time: Kia's own KSDS letters do use lifetime language. The PI1802, PI1803 and PI1805 dealer letters promise "lifetime engine warranty coverage for this issue only (DTC P1326)", so ask by campaign number and under the settlement.

What 268 rod-bearing bulletins say about who does what

We pulled every Hyundai and Kia manufacturer communication whose summary mentions a connecting rod, a rod bearing, a knock sensor or KSDS. That is 4,247 model-year rows collapsing to 268 distinct documents, dated 14 October 2016 to 1 May 2026.

Kia wrote 213 of them, Hyundai 55. That is a difference in filing habits rather than in engines — Kia publishes dealer memos, owner letters, Q&A sheets and reimbursement forms as separate documents — but it has a practical consequence: a Kia owner asking "is there anything published about my engine" is asking about a much thicker stack.

234 of 268 (87.3%) mention software, an ECU logic change or KSDS. Thirty-two mention a warranty extension. Read those two numbers together and the shape of the response is visible: the overwhelming majority of the paperwork written about this defect since 2016 installs a listener, and a small minority pays for the repair it listens for.

The campaigns that have no NHTSA number now have names. This guide used to say the standalone knock sensor campaign has no campaign number because it is a non-safety field action. True, and incomplete — the field actions have manufacturer numbers, and they are in the file. Kia ran PI1802 (2014-2018 Optima and Sportage, 2015-2018 Sorento), PI1803 (2011-2014 Optima, 2012-2014 Sorento, 2011-2013 Sportage) and PI1805 (2019 Optima, Sorento, Sportage), each described as "a software update to the Engine Control Unit (ECU) to install the Knock Sensor Detection System (KSDS) in order to protect the engine," with companion bulletins titled "Engine replacement instructions for DTC P1326." Hyundai ran Campaign 953 for the software and Campaign T3G for the inspection and replacement. Those are the numbers to say at a counter that tells you nothing is showing.

The renotification flights are the part nobody predicted. NHTSA's EA21-003 closing resume records that in December 2023 both makers agreed to renotify owners every eight months for three years. That commitment is visible in this file as documents: eight Kia owner renotification bulletins dated across 2025 — PI2002B, PI2102, PI2103, PI2104, PI2105, PI2106, PI2107, PI2108 — and eight more in 2026 through 1 May, several labeled "Flight 501." If you own one of these cars and think the mail stopped years ago, it did not. Download all 268.

What a dealer actually does with a Hyundai-Kia knock, checkpoint by checkpoint

Checkpoint 1 — the VIN question. "Which campaign numbers did you run this VIN against, and what did each one return?" Ask for the numbers, not the verdict. "Nothing open" and "not in 17V-224" are different answers.

Checkpoint 2 — the build date question. "What production date does the system show, and does it fall inside the window in the report?" A service adviser working from model year alone gets some of these wrong in both directions.

Checkpoint 3 — the engine question. "Is this the 2.4 GDI, the 2.0 turbo GDI or the V6?" One line, and it decides whether a Sportage or a Sorento is inside 17V-224 at all.

Checkpoint 4 — the inspection result. "What did the engine inspection measure, and can I have that on the invoice?" A pass is a reading on a date, and that date is the baseline for every later argument.

Checkpoint 5 — the part and warranty question. "Short block or complete engine, what is not included, and what warranty attaches to the part?" The two Hyundai reports do not use the same words for the same remedy, and the difference is a cylinder head. Get it in writing the day it is fitted — the dispute guide covers what to do when the answer changes later.

Three diagnostic traps that cost Hyundai and Kia owners the most

Trap 1: the recall checked by model year instead of VIN. The situation: a 2013 Santa Fe Sport at 96,000 miles with a knock that climbs with revs. What the shop says: "There's nothing showing for a 2013 Santa Fe Sport." What is really happening: 17V-226 defines its Santa Fe Sport population by production dates of 28 June 2012 through 31 May 2014, not by model year. A model-year answer is not a VIN answer. Price versus bill: $0 under the campaign, against an owner-reported median of $6,000 outside it. Your protective question: "Which campaign numbers did you run against this VIN, and what production date does the system show?"

Trap 2: the software update presented as the repair. The situation: a 2012 Optima that set P1326 and came back from the dealer with a software campaign on the invoice. What the shop says: "We updated the knock sensor system, you're all set." What is really happening: the update watches the bearing and limits the engine. The bearing after it is the bearing from before it. Price versus bill: a $0 software line, against the engine it was built to warn you about. Your protective question: "Did the bearing inspection run as well as the software, and what did it measure?"

Trap 3: the "engine" that turns out to be a short block. The situation: a 2013 Sonata approved for campaign work, with the owner expecting a complete engine. What the shop says: "Hyundai is replacing the engine." What is really happening: the reports do not use one word for one remedy. 15V-568 says dealers will "inspect, and if necessary, replace the engine assembly." 17V-226 says they will "replace the engine sub-assembly (or 'short block')." A short block is the bottom end; head and ancillaries are a separate conversation. Price versus bill: $0 either way inside the campaign; outside coverage the same partial-versus-complete distinction shows up in one owner report as "$7,700 before tax for a re-manufactured engine and over $12,000 for a fully assembled engine." Your protective question: "Under this campaign, is the part a short block or a complete engine, and what is not included?"

Three Hyundai-Kia knock quotes, decoded

These are composite scenarios, not individual customers — the mileages, quotes and outcomes are typical of the pattern each item describes, assembled so the arithmetic is visible. We do not publish invented testimonials, so nothing below is presented as a specific person's story. The dollar figures quoted are owner-reported amounts drawn from NHTSA's public complaint database.

Scenario 1 — the lanes behind one failure. Take a 2013 Sorento with a seized engine and no live coverage. One complaint in our sample records being "quoted $7,700 before tax for a re-manufactured engine and over $12,000 for a fully assembled engine" in the same conversation. Lesson: ask for all three lanes quoted separately — used, remanufactured, new — because the first number offered is rarely the cheapest available.

Scenario 2 — the knock that was a VIN question. Take a 2012 Sonata at 88,000 miles with a knock that climbs with the tachometer. Ask for the campaign check first and the build date is either inside 15V-568's 11 December 2009 to 12 April 2012 window or outside it. Inside, the inspection and any replacement are campaign work. Outside, the same car collects a paid teardown on the way to the same conclusion. Lesson: on these cars the free step is not a shortcut past diagnosis — it is the diagnosis, and it happens to be paid for.

Scenario 3 — the document that replaced the clock. Take a 2011 Sonata inside 15V-568, whose 2015 remedy raised the short block warranty "to 10 years/120,000 miles." Ten years from a 2011 sale ran out in 2021, and an owner told that on the phone hears a closed door. The open one is the settlement's lifetime term (22-EM-001H, January 2022): the same failure on the same car becomes a Limited Lifetime Warranty question. In our complaint set, 26.0% of the mileage figures are already past 120,000 — a quarter of these failures happen where only the newer document reaches. Lesson: when a warranty has been rewritten, quote the current bulletin number, not the recall you remember.

Best and worst Theta II years to own, and what the lists get wrong

What the documents say instead. 15V-568 names its own production fix: "The cleaning process was revised in April 2012 to utilize a hydraulic pressure 'wet blast' process to clean the crankshaft oil passages." If that had ended it, the story would stop there. It does not — 17V-226, filed eighteen months later, covers Sonatas built through 29 May 2014 and names no production correction date at all. Kia's 17V-224 puts its improvement in "August 2013 at the Hwasung plant and during the production of the 2014 model year," while still including 2014 Optimas built to 15 May 2014.

Where the lists are actively misleading. They rank by model year; every document here ranks by build date and engine. A 2013 Sonata built in February 2012 sits outside 17V-226's window, which opens on 21 March 2012 — while 15V-568 was still accepting 2012-model cars built up to 12 April. Three weeks of calendar are covered by two different reports for two different model years, and a month of build date moves a car from one document to neither. No years-to-avoid list can express that.

The honest ranking, by what it costs you.

• Best position: a car with a completed campaign inspection documented against the VIN, ideally one that received a replacement short block or engine with its own written warranty.
• Buy with the VIN out: every 2011-2014 Sonata, Optima, Sorento and Santa Fe Sport. The lookup is free and it is the whole due diligence.
• The worst position is not the worst year. It is the car that looks covered and is not: a 2.4 Sportage, a V6 Sorento, or a model-year match whose build date falls a month outside the window.

Before you buy one, in order: run the VIN, read the door jamb build date against the windows above, confirm the engine rather than the badge, start it cold and listen at 2,500 rpm, and ask whether an engine was ever replaced and when. Five minutes, no cost. The same exercise across the whole model: Sonata by mileage and Sorento by mileage.

After the engine work: verify, then prevent

Verify within a week. Campaign work documented against the VIN, campaign number on the invoice, the knock gone at the rpm where it lived, and the oil level checked at 500 miles — a fresh bottom end that uses oil is a conversation to have inside a warranty.

Keep the paperwork that proves scope. The invoice should name the campaign, the part fitted and the warranty in months and miles — that line is what makes a follow-up argument possible. Record thirty seconds from the same position before and after, too: the recording guide has the protocol.

Prevent what can be prevented. Oil to specification, on the short interval, and the level checked between changes. None of that undoes a machining defect, and it is the only lever an owner holds over bearing temperature.

Re-run the VIN once a year. A campaign completed on someone else's watch is invisible unless you ask, and our guide to warranty extensions covers why the coverage that pays usually has a deadline.

The Hyundai-Kia knock plan: 10 minutes, today, this week

Next 10 minutes — free: run the VIN, read the door jamb build date against the three windows, and confirm which engine is in it. On a Sportage or a Sorento that last fact decides the whole question.

Today:

4. If a campaign names your VIN, book the inspection and ask for the result in writing whichever way it goes.
5. If it knocks, record thirty seconds cold and at 2,500 rpm in neutral, and run it through a free sound check.
6. If the oil pressure lamp has been on, arrange a tow rather than a drive.

This week:

7. Start a measured oil consumption test even with no noise. It costs an oil change and gives you a number.
8. Get the dealer's service history for the VIN and find out whether an engine was ever fitted, and when.
9. If you paid for engine work in the past, ask about reimbursement against the plan named in your campaign's report.

Sources and documents

Primary documents. Every population, date and quoted phrase below was taken from the document itself — opened as a PDF, or read in NHTSA's flat files where no PDF is served, which is stated per item. The two places where we could not open a source are named in "What we looked for and did not find."

1. NHTSA 15V-568 / Hyundai 132 — Part 573, 10 September 2015. "Number of potentially involved: 470,000." 2011-2012 Sonata built at Hyundai Motor Manufacturing Alabama, 11 December 2009 to 12 April 2012. Remedy: inspect and "replace the engine assembly," plus increase "the warranty for the engine sub-assembly (short block) to 10 years/120,000 miles for both original and subsequent owners." PDF

2. NHTSA 17V-226 / Hyundai 162 — Part 573, 31 March 2017. "Number of potentially involved: 572,000," estimated 2% with defect. 2013-2014 Sonata built 21 March 2012 to 29 May 2014; 2013-2014 Santa Fe Sport built 28 June 2012 to 31 May 2014. Warnings, in order: knocking noise, "Reduced power and/or hesitation," check engine lamp, oil pressure lamp. NHTSA action RQ17-004. PDF

3. NHTSA 17V-224 / Kia SC147 — Part 573, 31 March 2017. "Number of potentially involved: 618,160," split as 443,825 Optima, 165,918 Sorento, 8,417 Sportage — the last being "All 2011-2013 MY Sportage vehicles equipped with the 2.0L Turbo Gasoline Direct Injection (T-GDI) engines." NHTSA action RQ17-003. PDF

4. NHTSA 18V-907 / Kia SC172 — Part 573, 19 December 2018. "Number of potentially involved: 68,127" — 50,051 Optima, 17,024 Sorento, 1,052 Sportage that "received an engine replacement under Recall No. 17v224." NHTSA's current public summary describes a wider population than this original report. PDF · Hyundai's twin 18V-934 covers 2011-2014 Sonata and 2013-2014 Santa Fe Sport "previously repaired under recall numbers 15V-568 and 17V-226." Record

5. KSDS recalls, remedy quoted from NHTSA's recall records — dealers "install a software update containing a new Knock Sensor Detection System (KSDS)": Hyundai 20V-746, 21V-727; Kia 20V-750, 23V-877.

6. NHTSA EA21-003, closed 5 February 2024 — defines KSDS as "an engine control software modification … intended to detect impending engine failure, alert the driver, and limit engine power," notes it "is being installed under recalls and non-safety field actions," and records that in December 2023 both makers agreed to renotify owners "every 8 months for the next 3 years." Investigation flat file

7. NHTSA RQ17-004 and RQ17-003, closed 22 December 2021 — same file. Consent Orders of 23 November 2020: Hyundai "agreed to a total civil penalty of $140,000,000," Kia "$70,000,000," over assertions including "the untimeliness of Recall Nos. 15V-568 and 17V-226" and that "Recall No. 17V-224 was untimely."

8. Theta II settlement agreement, the joint Hyundai and Kia document dated 9 March 2021; Final Approval Order 10 May 2021, judgment 10 June 2021, No. 8:17-cv-00838-JLS-JDE (C.D. Cal.). Source of the Class Vehicles and "Lifetime Warranty" definitions, the transfer clause and the 150,000-mile option. Settlement Agreement (PDF) · Final Approval Order (PDF) · Administrator's site

9. NHTSA AQ25-001, audit query into Kia's piston oil ring remedy, closed 18 December 2025 — source of Kia's statement of "the 10-year / 100,000-mile Powertrain warranty for original purchasers and a 5-year / 60,000-mile Limited Basic Warranty for subsequent purchasers." Same flat file.

10. Hyundai TSB 22-EM-001H, "Engine Warranty Extension (TXXI)," January 2022 — the Limited Lifetime Warranty on the long block for connecting rod bearing wear, "valid for original and subsequent owners," with the Campaign 953 and P1326 conditions in its boxed notice. PDF · superseded by 22-EM-001H-1, April 2022, which adds the Warranty Prior Approval requirement and the neglect, salvage and commercial-owner exclusions. PDF · Hyundai's dealer-facing "Engine Warranty Extension (TXXI) — Dealer Best Practice," 19 January 2022, lists the same vehicles and the inspection route. PDF

11. Kia warranty bulletins WTY007, WTY008 and WTY004, February and March 2017 — short block assembly coverage extended "to 10 years starting from the date of first service or 120,000 miles, whichever comes first, regardless of whether the vehicle owner is an original or subsequent vehicle owner," for 2011-2014 Sportage, 2012-2014 Sorento and 2011-2014 Optima, each with a reimbursement form. Read in NHTSA's manufacturer communications flat file (IDs 10090095, 10090117, 10094572); static.nhtsa.gov returns 404 for the PDFs. Manufacturer communications flat file

12. Our own analysis, published — by model, by model year, context shares, 268 rod-bearing bulletins, 242 owner-reported amounts, method file. CC BY 4.0.

13. Our earlier complaint sample — 15,206 complaints pulled from NHTSA's complaints API on 6 September 2026 for Sonata 2011-2014, Santa Fe Sport 2013-2014, Optima 2011-2014, Sorento 2012-2014 and Sportage 2011-2013; filings dated 17 March 2010 to 3 September 2026. complaintsByVehicle API

14. Hyundai TSB 22-EM-006H-2, "Engine Warranty Extension (TXXM)," November 2022 — engine repair for connecting rod bearing wear extended to 15 years or 150,000 miles on certain 2010-2021 Tucson, 2010-2012 Santa Fe, Veloster, Elantra, Elantra Coupe, Elantra GT and Sonata Hybrid vehicles with the listed engines; commercial entities and salvaged vehicles excluded. NHTSA document 10227316.

What we looked for and did not find. There is no open NHTSA investigation into the Theta II engine. We read the investigation flat file rather than trusting a search: PE19-003 and PE19-004 opened 29 March 2019 and closed 22 December 2021 on upgrade to EA21-003, which closed 5 February 2024, and both companies "have been released from the 2020-iniated Consent Orders (Kia since November 2022 and Hyundai since November 2023)." The open Hyundai and Kia entries concern ABS module fires, an air bag inflator and a rental-vehicle petition. Kia's own settlement site returned 403 to every client we tried, so Kia terms here come from the joint agreement filed on the Hyundai administrator's site, which covers both makers. And there is no NHTSA campaign number for the standalone KSDS campaign, because it does not have one: it is a non-safety field action, carrying manufacturer numbers instead — Hyundai Campaigns 953, 966 and 982; Kia PI1802, PI1803, PI1805, PI1806, PI2002A/B and PI2101-PI2108. Kia's own letters do carry lifetime language: PI1802, PI1803 and PI1805 dealer letters promise it "for this issue only (DTC P1326)" once KSDS is installed, alongside the settlement's term.

Sounds: noise index, knocking, ticking, ranked by cost, in NHTSA complaints. Money: diagnostic cost, dealer or independent, overcharging, disputing a bill. Sister guides: Sonata, Sorento, Telluride, warranty extensions. And our story.

Methodology. Campaign numbers, populations, production windows, remedy wording and warranty terms come from the Part 573 reports, NHTSA recall records, the investigation flat file and the settlement agreement itself, opened and read as text. Repair figures are owner reports, not audited invoices: dollar amounts were extracted only where a figure sat within 90 characters of both an engine word and a repair word inside a complaint describing engine failure or rod bearings, with purchase prices filtered out. Where a figure comes from a search-result summary we could not open, the article says so at the point of use. Eligibility depends on your VIN and build date, so verify before authorizing paid work.

Prices verified September 2026 and reviewed quarterly — no estimator site would serve our checks this pass, so the shop-price ranges are unchanged from that verification; the owner-reported figures on this page are ours and were recomputed on 18 September 2026. Technical documents verified September 2026: the recall reports, the two warranty-extension bulletins and the dealer best practice were opened and read again this pass.

Had a short block replaced under 15V-568, 17V-226 or 17V-224, or paid for an engine outside coverage? Email [email protected] with the year, engine, build date and odometer reading — owner data is how these ranges get sharper.