P0016 Code in 2026: $0 to $4,000, and Why 1 in 5 Reports Ends in an Engine

P0016 is the code that makes shops reach for the timing chain, and often they are right. It reports that the crankshaft and the camshaft on bank 1 no longer agree about where the engine is in its cycle — and the most common reason two shafts joined by a chain stop agreeing is that the chain between them has worn longer.

But "often" is not "always", and the manufacturer documents are full of exceptions. Kia fixes a P0016 on one Forte engine by resetting adaptive values with a scan tool and fitting no parts at all. GM has a bulletin for two identical connectors swapped during an engine repair, another for a reluctor ring that moved on the crankshaft, and another that exists purely because the timing marks on one engine family are hard to see, so chains get installed a tooth out.

By the end of this guide you will know which of five routes your P0016 belongs to, what proves it, and what each costs — from a 0.2-hour scan-tool reset to a $4,000 chain job. Claims marked 🟢 rest on a document in Sources, opened and read; ⚪ marks estimates and owner reports.

I built Pulscar — an AI tool that reads car problems from a 30-second recording — 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).

How to use this guide

Every route is defined by what happened just before the code appeared, not by the code itself.

One rule overrides everything: find out whether this engine has recently been apart. Three of the cheapest causes here exist only on an engine that has been worked on, and none is a worn part. That question costs nothing and reorders everything below it.

First: what P0016 says, and which cousin you have

P0016, P0017, P0018 or P0019? P0016 is the intake camshaft on bank 1, P0017 the exhaust camshaft on bank 1, and P0018 and P0019 the same pair on bank 2. A four-cylinder engine has only bank 1. P0017 is named alongside P0016 in 42 complaints — the tightest code pairing in the Check Engine Code Index. Two correlation codes on one bank point at something both camshafts share: the chain, a sprocket, or the crankshaft signal.

P0016 or P0011? P0011 says the intake cam is timed further advanced than commanded — a variable-valve-timing story: oil, a stuck solenoid, a phaser. P0016 says the two shafts do not line up at all. Our counts split them cleanly: of 107 P0011 complaints, 24 name the valve-timing hardware and 16 a chain; of 162 P0016 complaints, 5 name the hardware and 49 a chain.

Alone, or with a misfire? A misfire code or a flashing light outranks P0016 for urgency. The flashing light guide comes first if the engine is shaking.

The 10-minute driveway protocol

1. Read every stored, pending and history code and save the freeze frame. P0017, P0018 or P0019 alongside it changes the shape of the problem.
2. Ask what has been done to this engine recently. A chain job, a head, a harness, a replacement engine — three bulletins here apply only to those cars.
3. Start it from genuinely cold and listen at the front of the engine. A short metallic rattle that fades as oil pressure builds is the chain signature. Record 30 seconds.
4. Count the seconds before it fires. Long cranking means the computer is struggling to work out where the engine is.
5. Pull the dipstick. A hydraulic tensioner needs oil pressure, and a starved one cannot hold a chain tight.
6. Read the engine code off the service parts label. On GM trucks this one fact decides whether a federal recall applies.
7. Run the VIN through NHTSA's recall lookup and the owner site. No campaign names P0016, but one large recall uses it as its pass or fail test.

Ten minutes, a cheap reader and a phone, and you have done most of what a $80 to $200 diagnostic fee buys. What a diagnostic should cost covers the rest.

Find your situation: six ways people arrive here

"The code appeared days after an engine or chain job." → Route 1. The cheapest branch on the page.

"P0016 with P0017 as well." → Route 4 first. Two correlation codes on one bank point at something shared.

"2021-2024 GM full-size truck or SUV with the 6.2." → Route 5, and run the VIN today.

"2011-2014 F-150 with the 3.5 EcoBoost, rattle on cold start." → Route 4. Ford published a chain kit for exactly this.

"Engine stalled, will not restart, code read after the fact." → Route 5. Stop cranking and get it inspected.

"Code is intermittent and clears itself." → Route 2. Signals do that; worn chains generally do not.

What actually determines your number

Whether the engine has recently been apart. A hard P0016 that appeared after a repair has a documented, cheap cause far more often than one on a car nobody has touched.

Which codes came with it. P0017 alongside P0016 points at the chain or the crankshaft signal. A lone P0016 leaves the sensor branch open.

Whether there is a noise. A cold-start rattle from the front of the engine moves the chain to the front of the queue and changes the number by a factor of ten.

Access. Reaching the chain is 4 to 6 hours on friendly designs, 6 to 8 on most trucks and SUVs, and 8 to 12 or more on some luxury engines, which is why labor is the larger half of the bill.

Your engine code. On GM's full-size trucks, the difference between the 6.2L L87 and everything else is the difference between a federal recall and an invoice.

How long you wait. A chain caught while it is only noisy is a chain job. A chain that jumps a tooth on an interference engine is an engine.

The price ladder: read it from the bottom up

Read it from the bottom up: the top line and the bottom line can be the same engine, separated by a VIN. The chain, phaser and labor figures come from our timing chain cost guide, so the numbers match.

Your number, by what you drive

These are the makes that dominate the complaint file for this code, with the documents that name them. Raw counts across very different sales volumes: not a reliability ranking, and it cannot be turned into one.

Two rows are worth reading twice. The Kia Forte row is the cheapest documented P0016 repair we found anywhere: a stuck assembly, a scan-tool reset, no part fitted. The Cadillac CT6 row is the most expensive: a sprocket broken in manufacture, and a bulletin whose correction is a new engine, published against twenty-eight specific VINs.

Which route is yours? Five questions

1. Has this engine been apart in the last few months? → Route 1. Base timing, connectors, reluctor clocking.

2. Intermittent, with no noise and no drivability symptom? → Route 2. Sensors, connectors and software.

3. Oil low or overdue, or a whirr under load rather than a rattle at start-up? → Route 3. The actuator.

4. Metallic rattle at cold start, long cranking, or P0017 alongside? → Route 4. The chain.

5. Already stalled and refused to restart, or a 6.2L GM V8? → Route 5. Run the VIN first.

The five routes, cheapest first

Route 1 · The code came back from a repair — base timing, connectors and reluctor clocking

The tell. The engine has been apart in the last few months — a chain, a head, a harness, a replacement engine — and P0016 appeared afterwards, usually as a hard code with a rough idle.

What it actually is. Three ways a correct repair produces a wrong signal. GM's 23-NA-091, for 2016-2023 Cadillac, Chevrolet and GMC models with the 3.6L LGX or LGZ, is the clearest: dealers find P0016 or P0018 "after an engine repair of the engine wiring harness on the right front side of the engine. This will be a hard code and will usually cause a rough idle concern," because the connectors for the bank 1 intake camshaft actuator solenoid and the intake actuator park lock solenoid "have been swapped. These two connectors are identical and can only be identified by wire color in the connector." 🟢 GM's PIP5554A covers the second way on 2014-2019 Gen 5 V6 and V8 engines: "P0016 setting after internal engine repair" because "The engine Base timing is not being set correctly" — the timing marks are hard to see straight on, so the bulletin teaches a technique of counting chain links instead. 🟢 Kia's PS731 covers the third: after an engine replacement the camshaft reluctor wheel may not be correctly clocked at top dead center and is "sending an erroneous signal to the PCM." 🟢

The cheap cause that gets skipped. Asking the question. None of these has a part number attached; they are diagnosis and correction, invisible unless somebody asks what was done to this engine and when. GM's PIP5571 adds a fourth version on the 2017-2018 Colorado and Canyon: "two connectors being swapped during a repair causing a P0016 code to set." 🟢

Fix it yourself — build the timeline before the appointment. Write down every repair on this engine in the last year with dates, mileages and the shop, and take that page in. If the same shop did the work, say plainly that you want the repair checked before parts are quoted. The honest limit: verifying base timing or a reluctor position means the front of the engine comes apart again.

Where this does not apply. On an engine nobody has touched, all four causes are off the table and you move to Route 2.

At the shop — say this: "This engine had work done on [date]. Before anything is quoted, please check base timing and the camshaft actuator connectors against the service information — GM has bulletins for both producing exactly this code after a repair."

Route 2 · The signal is wrong, not the timing — sensors, connectors and software

The tell. The code comes and goes, often with no drivability symptom: no rattle, no long cranking, normal oil. Sometimes a stall or no-start that clears on a key cycle.

What it actually is. The computer works out crank-to-cam correlation from two electrical signals, and both can lie. Kia's TSB ENG 170 is the cheapest outcome in this family: on 2017 Forte 2.0L MPI cars built 15 May 2016 to 26 April 2017, P0016 sets "due to a stuck intake CVVT assembly," and the whole correction is to "reset the adaptive values of the engine ECU using the KDS." 🟢 No parts at all. Subaru publishes ECM reprogramming files that remedy P0016 through P0019 across 2017-2024 Crosstrek, Forester, Impreza, Legacy and Outback models, and a separate set for the 2022-2024 BRZ. 🟢 NHTSA's recall query RQ22-002, closed 16 June 2025, separated two failure modes on Stellantis vehicles: a faulty crank or cam connector, already covered by recall 16V-907, and a faulty sensor, which outside the recalled population produced "a MIL, Diagnostic Trouble Code (DTC) associated with crank/camshaft position sensor, and subsequent visits to a dealership" rather than a loss of power. 🟢

The cheap cause that gets skipped. The reluctor — the toothed ring the sensor reads. When it moves, the sensor is innocent. GM's PIP5102 tells the technician with P0016 stored to "inspect the reluctor on the crankshaft. If the reluctor has moved replace the crankshaft." 🟢 PIP4548D covers the camshaft version across 2006-2015 Chevrolet, Buick, GMC, Pontiac and Saturn models: inspect whether the reluctor "has spun on the camshaft. The reluctor cannot be repositioned so the camshaft must be replaced." 🟢 Neither is cheap, but both are diagnoses a new sensor will not fix.

Fix it yourself — check the easy electrical things. With the engine off, inspect both sensor connectors for corrosion, spread terminals or a loose lock. Note whether the code is current, pending or history, and whether it has ever cleared on its own — a code that clears itself is behaving like a signal problem, not a worn chain. The honest limit: telling a sensor from a reluctor takes an oscilloscope on both signals.

Where this does not apply. A rattle on cold start or long cranking is not a signal problem. Go to Route 4.

At the shop — say this: "Before a sensor goes in, has the crank and cam signal been scoped together? And is there an adaptive reset or a reprogramming file for P0016 on this VIN — Kia and Subaru both publish ones that fit no parts."

How do you tell a worn timing chain from an electrical P0016 without opening the engine? Mostly by the first ten seconds of a genuinely cold start. A chain that has lost tension rattles: a short, gravelly metallic noise from the front of the engine that fades once oil pressure reaches the tensioner, and the fading is the diagnosis rather than the reassurance. A sensor, a connector or a mis-set adaptive value is silent, and its code tends to come and go rather than stay. Long cranking before the engine fires belongs with the chain, because the computer is struggling to work out where the engine is. Film 30 seconds of the engine running, parked, on a cold start, and Pulscar's free check returns a likely cause, a severity and a repair-cost estimate, or "inconclusive" — it does not decide whether the car is safe to drive. Free, no card, about ten minutes, and the report arrives by email.

Route 3 · The actuator is starved or stuck — oil, phasers and the VCT hardware

The tell. A whirr, buzz or rattle under load rather than at cold start. Oil that is low, dark or overdue. Often P0011 or P0014 stored alongside, because the same oil feeds both systems.

What it actually is. The camshaft actuator is a hydraulic mechanism inside the sprocket, and when it cannot hold position the correlation the computer expects breaks down. Land Rover's LTB00916NAS5, for Halewood-built LR2, Discovery Sport and Evoque models listed by VIN range, describes "a rattle noise ... from the engine compartment" with P0016, P0017, P0026 or P0341 stored, caused by "the 'stopper' in the intake camshaft Variable Cam Timing (VCT) actuator becoming detached." 🟢 GM's PIP5855, for 2021-2022 Silverado 1500, Sierra 1500 and CT4 models with the 2.7L L3B, names a "Failed Camshaft Position Actuator Magnet" for any combination of P0011, P0014, P0016 and P0017. 🟢 Ford's TSB 21-2224 puts a 2020-2021 Transit 3.5L version of the same family down to "the software in the powertrain control module." 🟢

The cheap cause that gets skipped. The wiring, and the oil. PIP5855 does not start with the magnet: it starts with "check for and correct any related wiring, terminal tension, crimp, or lock issues as needed." 🟢 And the oil behind the system is worth proving first — the P0011 guide covers what level, grade and pressure do to a phaser.

Fix it yourself — prove the oil, then stop. Check the level cold on level ground, check the grade on the filler cap against the manual, find the date of the last change. A hydraulic tensioner and a hydraulic phaser share one pump. The honest limit: anything behind the timing cover is shop work.

Where this does not apply. If the oil is right and the noise is a cold-start rattle that fades, that is the chain.

At the shop — say this: "If the actuator is coming off, the cover is already open — please inspect and report the chain stretch, the guides and the tensioner at the same time, in writing, so I am not paying for this access twice."

Route 4 · The chain has stretched past its limit

The tell. A short metallic rattle from the front of the engine in the first seconds of a cold start, fading as oil pressure builds. Long cranking. P0017 stored with P0016. In our complaint file, 49 of 162 narratives name a chain, guide or tensioner — the largest single category, and three times the share in the P0011 set.

What it actually is. A chain grows longer as its pins and rollers wear. The hydraulic tensioner takes up the slack, but only once oil pressure has built, which is why the noise lives in the first seconds after a cold start. Once the chain has slack the camshaft lags the crankshaft and the correlation check fails. Ford's TSB 17-0026 names it for one famous engine: 2011-2014 F-150 trucks with the 3.5L GTDI "built on or before 10-Oct-2014" may set P0016, and "This concern may be due to a worn primary timing chain. A kit has been developed to aid in the repair process." 🟢 Twenty-one of our 162 complaints are that truck, in exactly those four model years. GM's PIP3423K, covering 2004-2014 models across twenty nameplates, tells the technician that P0016 through P0019, P0008 or P0009 mean "inspect for loose timing chains or tensioners" and, if that finds nothing, check the crankshaft reluctor. 🟢

The cheap cause that gets skipped. Not buying the whole front of the engine. GM's 12-06-01-009F, for stretched chains on the 3.6L High Feature V6 across twenty nameplates built after 15 July 2006, is unusually blunt: "Idler gears, camshaft actuators, crankshaft driven gears and timing chain guides are being replaced unnecessarily and are not worn and should not be replaced." Guides come out only "in cases where the guide wear block surface is worn down into the base friction material." 🟢 That is the manufacturer telling its own dealers to take parts off the estimate. There is a smaller version too: GM's PIP4581B covers a rattle with P0016 or P0017 after a repair that required removing the crankshaft balancer, where the answer is to re-torque the balancer bolt. 🟢

Fix it yourself — record the evidence, do not do the job. The cold-start recording is the whole DIY contribution here, and it is a real one: the only free timing chain inspection that exists, and something a shop can compare against after the repair. The honest limit: a chain job is a front-of-engine teardown on a timing-critical assembly, not a driveway repair on any modern engine.

Where this does not apply. A chain does not stretch overnight. Our odometer data puts the median P0016 report at 87,730 miles with only 3 of 72 readings at or under 36,000, so a very low-mileage car with this code belongs in Routes 1, 2 or 3 first.

At the shop — say this: "Before a chain quote, I want the cold-start noise recorded, the cam-to-crank offset read on a scan tool, and a line-by-line estimate. GM's own bulletin says guides and idler gears should not be replaced unless the guide wear block is worn into the friction material — please price it that way."

Which P0016 repairs should a shop prove before it charges you? Three, and each has a document behind it. What was done to this engine recently, because GM publishes bulletins for swapped connectors, mis-set base timing and a mis-clocked reluctor producing exactly this code after a repair. Whether the crank and cam signals were scoped together and the reluctor inspected, because a reluctor that has moved makes a sensor look guilty and no sensor will fix it. And which parts on the estimate were inspected and found worn, because the manufacturer's own chain bulletin says idler gears, actuators and guides are replaced unnecessarily. Ask for all three in writing before the timing cover comes off. Pulscar's free sound check adds a first read on the cold-start noise, and the documents decide the rest.

Route 5 · The engine has already failed, and P0016 is the gate

The tell. The engine stalled and would not restart, there is a deep knock under load, or the truck is a 2021-2024 GM full-size model with the 6.2L V8. In our file, 37 of 162 complaints mention an engine being replaced, rebuilt or quoted — more than one in five.

What it actually is. On the largest cluster in our data, P0016 is not a diagnosis at all: it is a pass-or-fail gate on a federal safety recall. NHTSA recall 25V-274, filed by GM on 24 April 2025, covers 597,571 2021-2024 Cadillac Escalade and Escalade ESV, Chevrolet Silverado 1500, Suburban and Tahoe, GMC Sierra 1500, Yukon and Yukon XL vehicles with the 6.2L V8 (RPO L87) built 1 March 2021 to 31 May 2024, for connecting rods and crankshafts with manufacturing defects. Its dealer inspection begins: "1. Inspect/Check for DTC P0016. 1.1. If DTC P0016 is NOT SET, continue to step 2. 1.2. If DTC P0016 is set, DO NOT proceed with the rest of the service procedure, quarantine vehicle." 🟢 Trucks that pass receive "NEW 0W-40 Oil" and a new fill cap; trucks with the code set go to engine replacement. The Part 573 report records 28,102 field complaints or incidents potentially related to L87 failure, "of which 14,332 involved allegations of loss of propulsion." 🟢 The second document here is smaller and starker: GM's 17-NA-272, for 2016-2017 Cadillac CT6 and 2017 XT5 models listed by 28 individual VINs, traces a loud noise, a lit MIL and a no-start with P0016 to "a broken engine crank sprocket caused by incomplete machining. Failure of the sprocket will cause the timing chain to stop moving or break." Correction: "Replace the engine assembly." 🟢

The cheap cause that gets skipped. Reading the engine code before the badge. Recall 25V-274 is defined by RPO and build date, not by model year or nameplate, and the RPO is on the service parts label in the glovebox. Which GM truck noises the recall covers and which it does not is documented in the Silverado ticking guide, along with the special coverage GM issued for vehicles closed out under it.

Where this does not apply. Most P0016 cars are not in this route. It exists because one cluster dominates our recent data, and on that cluster the code decides who pays.

At the shop — say this: "Run this VIN against recall 25V-274 and tell me the engine RPO. If P0016 is stored and the truck is eligible, I understand the inspection is not performed and the vehicle goes to engine replacement — please confirm that in writing on the repair order."

What we counted in the federal complaint file

Our sample: every vehicle complaint added to NHTSA's public complaint files between 1 January 2015 and 8 September 2026, pulled 14 September 2026 and de-duplicated by report number: 777,040 unique owner reports. We matched the code case-insensitively — narratives are capitals through 2020 and mixed case after, and for this code a capitals-only search would be catastrophic, because 43.8 percent of the set arrived in 2025 and 2026.

162 complaints contain the whole word "P0016". Eight more rows held the five characters inside a longer string and were read in full and excluded. Worth saying plainly: five of those eight are almost certainly reporting this code — "P001600" is the six-digit extended form GM and several scan tools print. We excluded them anyway to keep this set identical to the one behind the Check Engine Code Index. Including them gives 167 instead of 162, a 3.1 percent difference that changes no finding here.

The safety profile, and the instrument that disagrees

The two tow figures are the story of this table. The structured field, the box someone ticks on the form, says 4 of 162. The word "tow" appears in 41 narratives — ten times as many. We publish both and average neither: the structured field is plainly under-filled here, and the narrative count is a floor of its own.

That gap matters because the flags alone would make this look like a paperwork code. It is not. Two of every five narratives describe the engine stopping, one in four ended with a tow truck, and one in ten says no warning came first. What the flags genuinely show is that the stops are not, in this file, producing crashes: one in 162 reports against a 4.37 percent baseline. The honest reading is a code that strands people rather than one that hurts them — and 162 reports is too small to prove even that.

What owners name, and what that does and does not prove

Each category is a case-insensitive pattern over the narrative. A complaint can fall into several, so the column does not add to 162. These measure what owners wrote down, not what a technician found.

The chain count was checked by hand. We drew 30 of the 49 matches at random and read them in context. Thirty of thirty are genuinely about a timing chain, guide, tensioner or a chain that jumped teeth. Observed false-positive rate: zero, and no tightening was needed — unusual, because most keyword counts we publish need two or three rounds.

The engine-replacement count is the headline, and it needs its caveat in the same breath. We drew 30 of the 37 at random and read them in full. All thirty describe a real engine replacement, rebuild or quote attached to that vehicle. One — a 2008 Mazda CX-9 — attributes it to a head gasket and coolant in the oil rather than to the timing fault. We left it in, because this number measures how often the complaint ends in an engine, not how often P0016 caused one. A narrower pattern requiring the replacement to have already happened returns 5 of 162; both are published, because 37 is how often the conversation reached an engine and 5 is how often the owner recorded it as done.

Does a P0016 complaint tell you what actually broke on your own car? Not by itself, and the shape of this file explains why. Every count above comes from people who filed a federal report, which is overwhelmingly the group whose problem was expensive, dangerous or unresolved. An owner whose chain was replaced under warranty at 40,000 miles almost never writes to NHTSA about it, and neither does the owner whose dealer reset an adaptive value for free and sent the car home the same afternoon. So the chain's 30 percent and the engine's 23 percent describe the expensive tail of this code rather than its frequency, and every one of them is a floor, because an owner who does not use a word is not counted. Read the table as a map of what goes wrong when P0016 goes badly. Pulscar publishes the underlying rows so anyone can check a specific call against the narrative it came from.

The number that separates P0016 from P0011

Same query, same eleven-year window, same exclusions, same reader. The two codes invert on the part owners name, and the correlation code ends in an engine two and a half times as often. It also arrives later — 87,730 miles against 76,222, with only one in nine readings inside a 5-year, 60,000-mile powertrain warranty against one in three for P0011. A P0011 has a meaningful chance of being someone else's bill. A P0016 usually does not, which is exactly why the free checks in Routes 1 and 2 matter before the front of the engine is opened.

Where those 162 reports sit on the odometer

Seventy-two of the 162 reports state a usable mileage, keeping readings strictly between 0 and 400,000.

Two things follow. This is a late-life code: eight of every nine reports that state a mileage are already outside a 60,000-mile powertrain warranty, and half the file sits between 73,000 and 114,000 miles. And the low-mileage cases are the interesting ones: only three readings are at or under 36,000 miles, which is where Routes 1 and 2 belong — a repair that went back wrong, or a signal that is lying. A chain does not wear out at 20,000 miles.

When the reports arrived, and the cluster behind the spike

Seventy-one of the 162 reports — 43.8 percent — arrived in the last twenty months, and the partial year 2026 is already the largest in the file. That looks like a trend and it is not one.

Strip out a single cluster and it collapses. Fifty-eight of the 162 complaints are GM full-size trucks and SUVs — Sierra 1500 26, Silverado 1500 18, Escalade 4, Yukon and Yukon XL 6, Tahoe 3, Suburban 1 — and 57 of those 58 arrived in 2025 or 2026. Remove them and the 2025-2026 total falls from 71 to 14. Twenty-six of the 58 name the 6.2L or the engine code L87, and eight name recall 25V-274 or GM's own campaign numbers.

The mechanism is the one we have measured on other codes: a recall that reaches 597,571 owners teaches them a five-character string, and some of them type it into a federal form. The line measures attention, not failure rate, and any page showing a rising P0016 chart without naming the cluster is showing you a recall mailing list.

Two other clusters have nothing to do with it. The Ford F-150 group is 21 complaints, all model years 2011 to 2014 — exactly the range of TSB 17-0026 — with reports arriving 2015 to 2023 and nothing since. The Mercedes-Benz group is 19 complaints, 17 of them model year 2006 or 2007, with 17 naming P0017 as well and 13 naming a balance shaft, idler gear or sprocket.

The document that does not exist, and the one that uses the code anyway

We searched every recall campaign in NHTSA's file for the string "P0016" in the defect description, the remedy text or the notes. The result is zero campaigns. The Check Engine Code Index, counting from the manufacturer communications file instead, independently reports zero warranty extensions or emissions campaigns among the 49 bulletins that name the code. The same query for "timing chain" in a defect description returns two campaigns in the whole 2015-2026 file, neither on a US passenger car — a Ducati motorcycle and a Mitsubishi Fuso truck. The one US passenger-car timing chain recall we found, GM's 07V-519, is from 2007 and covers 20,514 Saturn LS cars.

So a stretched chain is, with that twenty-year-old exception, a warranty-and-bulletin matter rather than a recall matter. But two documents use this code without naming it in a summary.

Recall 25V-274 uses P0016 as its gate. Covered in Route 5: the code decides whether an eligible GM truck is inspected or quarantined for an engine.

GM service updates N252510320 and N252510321 exist only to tell you about it. Released in August and September 2025 for 2023-2024 GM full-size trucks and SUVs, they reprogram the engine computer "to add to the existing Check Engine Light a Driver Information Center (DIC) warning message if DTC P0016 sets." 🟢 No parts, 0.4 hours, available over the air. The fault behind the code is untouched: GM decided the existing warning was not loud enough, which is in its way the strongest statement any manufacturer has made about how much this code matters.

What happens to a chain, and why the noise fades

This section exists because the rest of the page rests on it.

A timing chain does not stretch like a rubber band. Each link is a pair of plates on a pin; as pins and holes wear, every joint gains a fraction of a millimeter of play, and across a hundred-odd links that adds up to real slack. A hydraulic tensioner presses on a guide to take it up, using engine oil pressure.

Three consequences follow, and they are the whole diagnostic logic of Route 4.

The noise is a cold-start noise. After the engine sits, oil drains out of the tensioner. On the first start there is no pressure behind it for a second or two, so the slack chain slaps its guides. Once pressure builds the noise stops — which means the noise going away is not reassurance, it is the diagnosis.

The timing drifts before anything breaks. A longer chain lets the camshaft lag the crankshaft slightly, and the computer measures that lag as a correlation failure. That is why P0016 arrives with no noise at all in some cars and a rattle in others: the two symptoms have different thresholds.

The end is sudden. A worn chain can jump a tooth on its sprocket, usually under the highest load it sees, which is start-up. On an interference engine, valves and pistons then occupy the same space — the step from a $1,500 to $4,000 job to an engine. NHTSA's EA06-009 measured the consequence on one engine family: none of the vehicles that stalled from a chain failure could be restarted, about a third of the stalls happened above 40 mph, and around 20 percent of owners could not get the car out of traffic. 🟢 Stall-while-driving was estimated at 5.2 percent by GM and 7.0 percent by NHTSA at six years in service.

How to pull your own car's federal record in 10 minutes

1. Run the VIN for recalls. NHTSA's VIN lookup returns open, unrepaired safety and emission recalls for that exact vehicle. It does not show completed ones or special coverages, which is why step 2 is not optional.

2. Ask the brand's owner site, then a dealer. Ask in that phrasing: "every campaign on this VIN, open or closed, including special coverages and customer satisfaction programs — and the engine RPO." On a GM truck that last word is the whole answer.

3. Read the bulletins for your year, make and model. NHTSA republishes every manufacturer communication it receives: the field layout describes the columns, and the PDFs sit under static.nhtsa.gov with the document numbers used in Sources below. Our Check Engine Code Index does this across the seventeen most common codes.

4. Read other owners' complaints on the same car. NHTSA's public API answers a plain query with a make, model and model year, and the complaint field layout explains every column. One caution from our own use of it: the recall endpoint has returned a campaign against model years the campaign's own Part 573 report does not list, so confirm any year range against the PDF.

5. Write down the repair history of this engine. Dates, mileages and shops for anything that opened the engine or its harness. For this code, that page is Route 1.

6. File your own complaint if the answer is no. Every number here exists because owners did, and NHTSA screens those reports when deciding whether a pattern deserves an investigation.

What actually happens at the shop, checkpoint by checkpoint

Checkpoint 1 — the history question. "Has anything been off this engine in the last year?" Four documented causes live behind that answer, and none is a worn part.

Checkpoint 2 — the full code list. "Which codes are stored, pending and in history, and what does the freeze frame say?"

Checkpoint 3 — the signal test. "Have the crank and cam signals been scoped together, and was the reluctor inspected?" A reluctor that has moved will not be fixed by a sensor.

Checkpoint 4 — the VIN and the RPO. "What recalls, campaigns and special coverages show on this VIN, and what is the engine RPO?"

Checkpoint 5 — the estimate, line by line. "Which parts are being replaced because they were inspected and found worn, and which because they are in the kit?"

Three diagnostic traps that cost owners the most

Trap 1: the chain quoted from the code. The situation: a lone P0016, no noise, no long crank, on an engine that had a head gasket done three months ago. What the shop says: "P0016 is the timing chain. We are into the front of the engine." What is really happening: nobody has asked what was done to the engine. GM has three separate bulletins for P0016 appearing after a repair — swapped connectors, base timing set wrongly, a mis-clocked reluctor — and all three are diagnosis rather than parts. Price versus bill: $80 to $250 of diagnostic time against $1,500 to $4,000. Your protective question: "Has base timing and the actuator connector wiring been verified against the service information before we price a chain?"

Trap 2: the whole front of the engine. The situation: the chain genuinely is worn, and the estimate lists a chain kit, both idler sprockets, both camshaft actuators, the crankshaft driven gear and all the guides. What the shop says: "While we are in there, everything goes." What is really happening: GM's own bulletin for these engines says the opposite in plain words — those parts "are being replaced unnecessarily and are not worn and should not be replaced," with guides changed only where the wear block is worn into the friction material. Price versus bill: several hundred dollars of parts the manufacturer says to clean and reuse. Your protective question: "Which of these parts was inspected and found worn, and which is here because it comes in the kit?"

Trap 3: the sensor that was never the problem. The situation: an intermittent P0016, a camshaft position sensor fitted, and the code back within a month. What the shop says: "It must be a bad sensor again, or the chain after all." What is really happening: the sensor reads a toothed reluctor, and a reluctor that has spun or moved produces a sensor-shaped fault that no sensor will fix. GM publishes this for both the crankshaft and the camshaft version. Price versus bill: one oscilloscope test against a second sensor and then a chain quote. Your protective question: "Before another part, can both signals be scoped together and the reluctor inspected?"

Three quotes, decoded

These are composite scenarios, not individual customers — the mileages and outcomes are typical of the pattern each describes, assembled so the arithmetic is visible. We do not publish invented testimonials.

Scenario 1 — the repair that came back wrong. A 2019 V6 crossover at 68,000 miles, P0016 as a hard code with a rough idle, two weeks after a valve cover and harness repair. The first estimate is a chain at $2,600. The owner points at the repair date and asks for the actuator connectors to be checked against the service information. Two identical connectors had been swapped. Diagnostic time only. Lesson: the cheapest cause on this page is a question about the calendar.

Scenario 2 — the chain, priced twice. A 2012 V6 crossover at 128,000 miles, P0016 and P0017, a short metallic rattle on cold start. The first estimate lists a chain kit, both actuators, idler sprockets and every guide at $3,900. The owner asks which parts were inspected and found worn, quoting the manufacturer's bulletin. The revised estimate keeps the kit and one guide, landing near $2,700 — still a large bill, still the right repair. Lesson: the question that saves money here is not "how much" but "which of these was inspected".

Scenario 3 — the VIN that changed the answer. A 2022 full-size truck at 41,000 miles loses power on a highway and will not restart. An independent shop reads P0016 and quotes a used engine at five figures. The owner reads the engine RPO off the service parts label, finds the 6.2L L87 and an open recall, and has the truck moved to a dealer. Under 25V-274 a stored P0016 means the inspection is skipped entirely and the vehicle goes to engine replacement at no charge. Lesson: on one very large group of vehicles, the engine code in the glovebox beats any diagnosis.

Should you buy a used car with a P0016 in its history?

This is the adjacent question people actually ask, and for this code the answer leans harder than usual.

A P0016 that ended in a documented chain job is not a reason to walk away. A chain, guides and tensioner replaced with an invoice naming the parts is a car with a fresh front end, and our data puts the code at a median of 87,730 miles — the work was due.

A P0016 with no paperwork on a high-mileage car is a different object. Twenty-three percent of the complaints mention an engine. On a private sale, plug in a reader yourself and read current, pending and history codes before money moves.

Three things to check on any car whose history mentions this code. The cold start: those first ten seconds are the only free chain inspection that exists, so hear the car started from genuinely cold. The crank time: long cranking with this code in the history is a bad combination. The repair record: if a chain was done, ask which parts went in, because a kit fitted without addressing a worn guide comes back.

Where we would genuinely hesitate. A 2011-2014 F-150 with the 3.5L EcoBoost, a cold-start rattle and no chain invoice; a 2006-2007 Mercedes V6 with P0016 and P0017 stored; or any car where the code is live and the seller has cleared it once. Each is asking you to buy a $1,500 to $4,000 job with someone else's name on the receipt.

Where we would not hesitate. A 2021-2024 GM truck whose recall work is recorded as complete, with an engine replaced under 25V-274 and the paperwork to show it. The Silverado ticking guide covers what that paperwork should say.

After the fix: verify, then prevent

Verify the monitor, not just the light. Drive a week, then check with your own reader that P0016 has not returned as pending and the readiness monitors have run.

Record the cold start again. Same spot, same phone, same cold engine. A recording made after the repair is the only way to prove the rattle actually went.

Protect the new chain with oil. A hydraulic tensioner runs on oil pressure, and a long interval starves it. The timing chain guide is explicit that a chain has no replacement interval — the only preventive spending this system has is oil on schedule.

Keep the invoice specific. It should name every part fitted and the inspection result for the parts that were not.

Your action plan: 10 minutes, today, this week

Next 10 minutes — free:

1. Read and save every stored, pending and history code plus the freeze frame. Do not clear anything.
2. Write down every repair this engine has had in the last year, with dates and mileages.
3. Check the dipstick and note the level and color.

Today:

4. Start the engine cold, record 30 seconds from the front, and count the seconds before it fires.
5. Read the engine RPO off the service parts label and run the VIN through NHTSA's recall lookup.
6. Run a free sound check before anyone quotes a chain.

This week:

7. If the engine has recently been apart, get base timing and the actuator connectors checked first.
8. If not, get the crank and cam signals scoped together and the reluctor inspected before a part is fitted.
9. Only then price a chain — line by line, with the inspection result beside each part.

Sources and documents

Primary documents only. Where a claim is marked 🟢 it rests on an item below, opened and read, with every date, population and quoted phrase taken from the document itself. Claims marked ⚪ are estimates or owner reports.

1. NHTSA recall 25V-274, Part 573 submitted 24 April 2025, GM number N252494000 — 597,571 vehicles with the 6.2L V8 (RPO L87) built 1 March 2021 to 31 May 2024. The dealer bulletin's first step: "Inspect/Check for DTC P0016 ... If DTC P0016 is set, DO NOT proceed with the rest of the service procedure, quarantine vehicle." The report as submitted states 597,630; the difference is recorded in our method file. Part 573 (PDF) · Dealer bulletin (PDF) · Campaign record
2. GM 17-NA-272, August 2017 — 2016-2017 Cadillac CT6 and 2017 XT5, LGX or LGW V6, listed by 28 VINs: "a broken engine crank sprocket caused by incomplete machining"; correction, "Replace the engine assembly." Bulletin (PDF)
3. GM 12-06-01-009F, March 2015 — 3.6L High Feature V6 timing chain kits across twenty nameplates: "Idler gears, camshaft actuators, crankshaft driven gears and timing chain guides are being replaced unnecessarily and are not worn and should not be replaced." Bulletin (PDF)
4. GM 23-NA-091, May 2023 — 2016-2023 Cadillac, Chevrolet and GMC 3.6L: P0016 or P0018 after a harness repair, from two identical connectors swapped. Bulletin (PDF)
5. GM PIP5554A, published 7 February 2019 — 2014-2019 Gen 5 V6 and V8: "P0016 setting after internal engine repair ... The engine Base timing is not being set correctly." PIP (PDF)
6. GM service update N252510320, 8 September 2025 (with N252510321) — 2023-2024 GM full-size trucks and SUVs: software "to add to the existing Check Engine Light a Driver Information Center (DIC) warning message if DTC P0016 sets"; 0.4 hours or over the air. Bulletin (PDF)
7. GM PIP5855, 18 May 2022 — 2021-2022 Silverado 1500, Sierra 1500, CT4 and CT4-V, 2.7L L3B: failed camshaft position actuator magnet, with wiring and terminal tension checked first. PIP (PDF)
8. Ford TSB 17-0026, 12 May 2017 — 2011-2014 F-150 3.5L GTDI built on or before 10 October 2014: P0016 "may be due to a worn primary timing chain. A kit has been developed to aid in the repair process." Read in NHTSA's manufacturer communications flat file; the PDF was not retrievable at the static paths tried. Field layout
9. Kia TSB ENG 170, June 2017 — 2017 Forte 2.0L MPI built 15 May 2016 to 26 April 2017: P0016 "due to a stuck intake CVVT assembly," corrected by resetting ECU adaptive values with the KDS. No parts. Bulletin (PDF)
10. Kia PS731, May 2022 — Soul, 2010 to date: P0011, P0014, P0016 or P0017 after an engine replacement from a camshaft reluctor wheel clocked wrong at top dead center. Pitstop (PDF)
11. Land Rover LTB00916NAS5, 18 May 2018 — LR2, Discovery Sport and Evoque built at Halewood: a rattle with P0016 from the "stopper" in the intake VCT actuator detaching. Bulletin (PDF)
12. Subaru 09-120-24 (2017-2024 Crosstrek, Forester, Impreza, Legacy, Outback) and 09-128-24 (2022-2024 BRZ) — ECM reprogramming files that remedy P0016 through P0019. Bulletin (PDF)
13. GM PIP5102, PIP3423K, PIP4548D, PIP5571, PIP4581B, PIP5730A, Ford TSB 21-2224 and GM PIP6082 — reluctor movement, loose chains, swapped connectors, balancer-bolt torque and cam-actuator debris, all read in NHTSA's manufacturer communications flat file. Field layout
14. NHTSA engineering analysis EA06-009, closing resume 9 November 2007 — timing chain failure and stall while driving on 2001 Saturn L-Series cars; none of the stalled vehicles could be restarted, about a third of the stalls were above 40 mph; stall-while-driving estimated at 5.2 percent (GM) and 7.0 percent (ODI) at six years. Closed on recall 07V-519, 20,514 vehicles. Campaign record
15. NHTSA recall query RQ22-002, opened 22 July 2022, closed without action 16 June 2025 — crank and camshaft sensor failure modes on Stellantis vehicles, and the population of recall 16V-907 (42,231 2016 Journey, Compass and Patriot). Campaign record
16. Our P0016 complaint analysis — all 162 complaints by make, model, model year and year of report; the parts owners name, with the sample readings behind each count; safety flags against the baseline; odometer bands. Method · by make and model (CSV) · what owners name (CSV) · model year and report year (CSV) · outcomes and mileage (CSV) · CC BY 4.0
17. Our complaint sample — 777,040 unique complaints added 1 January 2015 to 8 September 2026, pulled 14 September 2026. NHTSA complaint file layout
18. Pulscar Check Engine Code Index — the bulletin-side counts quoted here (49 bulletins, 7 groups, 27% software, zero coverage campaigns, the N252510320 and N252510321 warning-message updates) come from the index and are not recomputed. Index and data

What we looked for and did not find. No recall campaign names P0016, and no warranty extension or emissions campaign appears among the 49 bulletins that do. We looked for a manufacturer statement giving a mileage at which a timing chain should be replaced as maintenance and found none, which matches our timing chain guide: a chain has no service interval.

Codes: check engine light, the code index, P0011, P0300, P0420, flashing light. Timing and oil: timing chain cost, oil change cost, low oil pressure. Noises: knocking, ticking, Silverado ticking. Money: diagnostic costs, overcharging, our story.

Methodology. Populations, build windows, labor times and quoted phrases come from the documents above, downloaded from static.nhtsa.gov or read in NHTSA's flat files on 19 September 2026. Complaint counts come from NHTSA's public complaint files, de-duplicated by report number; they are owner reports, not audited repairs, and 162 is a small set dominated by one cluster. Price ranges are estimates carried forward from our timing chain and diagnostic cost guides so the figures match across pages, and are marked ⚪.

Prices verified August 2026 and reviewed quarterly — no estimator site would serve our checks in this pass, so the chain, labor and parts ranges are carried forward unchanged from the timing chain guide they come from and remain marked as estimates. Technical documents verified September 2026: every bulletin, Part 573 report and investigation resume cited above was downloaded or read in the federal flat files on 19 September 2026.

Had P0016 diagnosed, or paid for a chain that did not fix it? Email [email protected] with the year, engine, mileage, what the cold start sounded like and what finally cleared the code — owner data is how these ranges get sharper.