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

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 mechanism every time: metal debris left in the crankshaft during machining, restricting oil to the bearings.

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 — an AI tool that identifies car problems from a 30-second recording — after spending $6,000 on misdiagnosed repairs, starting with a $380 bill for an "engine knock" that turned out to be a loose heat shield and a $5 zip tie.

How to use this guide

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 boot 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.

Find your situation: eight ways people arrive here

"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. The update did what it was built to do.

"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 your 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.

Whether the warranty clock has run. 15V-568 raised the short block warranty "to 10 years/120,000 miles for both original and subsequent owners" — generous on paper, finite in practice. A 2011 Sonata first sold in 2011 passed ten years in 2021 regardless of odometer.

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 price ladder: read it from the bottom up

Your 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 the 2011-2012 Sonata row is the only one with a written warranty extension in numbers, which makes it the only one with a clock you can watch expire.

Which route is yours? Five questions

1. Does the knock speed up when you rev in neutral? No → not the Theta II story; start at the parent knocking guide. Yes → keep going.
2. Is your build date inside 15V-568, 17V-226 or 17V-224? Yes → Route 1.
3. Has the knock sensor software been done, or is P1326 stored? Yes → Route 2.
4. No knock yet, but it uses oil between changes? Yes → Route 3.
5. Has an engine already been fitted to this car? Yes → Route 4. None of the above → Route 5.

The five 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 memorising: "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 litre 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. Check-engine light, the car goes soft and will not pull, and a scan returns P1326. In our sample, 83 complaints name P1326 by number and 173 describe limp mode, reduced power or a failure to accelerate.

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 is specific enough to shortcut an argument, and any parts counter reads it for nothing. 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 and 23V-877 do the same across Sorento, Forte, Optima Hybrid, Soul and Sportage.

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. Record thirty seconds and Pulscar's AI compares the acoustic signature against catalogued failure patterns, then returns the likely cause, whether it is safe to drive, and the fair 2026 price. Free, no card, no subscription, about ten minutes. The report arrives by email as a PDF, 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. Pulscar tells you which noise you have before you find out 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 identifies 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 authorising 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. Record thirty seconds and Pulscar tells you which family of noise you have.

What actually happens at the dealer, 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 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 clock, not the odometer. Take a 2011 Sonata inside 15V-568, whose remedy raised the short block warranty "to 10 years/120,000 miles for both original and subsequent owners." A car first sold in 2011 passed ten years in 2021 with the mileage allowance largely unused: in our sample, 124 of the 150 mileage figures recorded near an engine failure sit under 120,000 miles. Lesson: with an extension written as years or miles, whichever comes first, it is almost always the years that end it — and nobody mails you a letter on that date.

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 two and a half years 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, while a 2012 Sonata built in March 2012 sits inside two overlapping windows at once — 15V-568 runs to 12 April 2012 and 17V-226 opens on 21 March 2012. 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.

Your situation right now: four playbooks

"It knocks and it climbs with the revs." Stop driving it if the oil pressure lamp is on, and run the VIN today against all three campaign numbers. Record thirty seconds cold first: it is free, and it stops existing the moment the engine is opened.

"P1326 is stored and the car has gone soft." That is the detection system working. Ask for the bearing inspection result in writing and the date the software campaign was applied, then ask which warranty covers what it found.

"No noise, but it drinks oil." Start the measured consumption test today: change the oil, note the odometer, read the dipstick every 500 miles. The cheapest lane in this guide, and the only thing that wastes it is guessing instead of measuring.

"An engine was already fitted and it knocks again." Get the original repair order, find the part number and the warranty terms attached to it, and record the current knock before anyone opens anything. A replacement failing again is a recurring pattern in our sample, not a freak event.

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.

Your action plan: 10 minutes, today, this week

Next 10 minutes — free:

1. Run the VIN through NHTSA's recall lookup and write down every campaign, open and completed.
2. Read the build date off the door jamb and compare it to the windows for 15V-568, 17V-226 and 17V-224.
3. Confirm which engine is in it. On a Sportage or a Sorento that 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 only. Every population, date and quoted phrase below was taken from the document itself, opened and read.

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. Our 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

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.

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 authorising paid work.

Prices verified: September 2026 · Technical documents verified: September 2026 · Reviewed quarterly

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.