P0016 means the engine control module compared the signal from the crankshaft position sensor against the signal from the camshaft position sensor on bank 1 and found the two out of the timing relationship it expects. That is a different kind of fault than a sensor going dead. This article covers the seven real mechanical and electrical causes, how a shop actually narrows them down, what each one costs to fix, and why chasing the sensor first is the single most common way people waste money on this code.
The table below is the short version. Read the “How Urgent” column before anything else if the check engine light just came on.
| Cause | Telltale Sign | Typical Cost |
|---|---|---|
| Stretched timing chain | Rattle on cold start, code returns after clearing | $400 – $1,800 |
| Worn chain guides/tensioner | Chain slap noise, timing drifts more at idle than at speed | $500 – $1,800 |
| Failed VVT phaser/actuator | Rattle for 1–3 seconds right at startup, disappears once oil pressure builds | $250 – $700 per phaser |
| Low or degraded oil pressure to the phaser | Overdue oil change, wrong viscosity, or low oil level | $40 oil change – $600 oil pump |
| Clogged VVT oil control valve screen | Code sets more often when cold or after a long idle | $60 – $250 |
| Skipped timing chain tooth | Rough idle, misfires, code sets immediately after a timing-related repair | $600 – $2,000 |
| Camshaft or crankshaft sensor fault | Code is intermittent, no unusual noise from the front of the engine | $80 – $250 |
Stop driving if the code is accompanied by a rough idle, a noticeable loss of power, or a rattling noise from the front of the engine that continues after startup. Those signs point toward actual timing chain slack rather than a sensor or wiring fault, and a chain that jumps further can bend valves on interference engines. A P0016 with no drivability symptoms and no noise is reasonable to drive on for a few days while you get it diagnosed, but do not ignore it indefinitely.
What P0016 Actually Means
Every modern engine times two things against each other: where the crankshaft is (which cylinder is coming up) and where the camshaft is (whether that cylinder is on its intake or exhaust stroke). The crankshaft position sensor and camshaft position sensor each report their own signal to the engine control module, and the module checks that the two arrive at the expected angular relationship — typically within a few degrees of crank rotation, depending on the manufacturer.
P0016 sets when that relationship falls outside the acceptable window on bank 1 (the bank containing cylinder 1) using sensor A, which on most applications is the primary crank sensor and the intake camshaft sensor. This is the detail that matters: P0016 is a correlation code, not a circuit code. A circuit code like P0335 (crank) or P0340 (cam) means the module got no valid signal at all — open circuit, short, or a dead sensor. P0016 means the module is receiving valid signals from both sensors, but the timing between them has drifted. That almost always points to something physically moving out of position — a stretched chain, worn guides, a lazy VVT phaser — rather than a sensor that needs replacing.
Freeze frame data is worth pulling before anything else. Note the engine RPM and load at the moment the code set. A correlation fault that only appears at idle or immediately after a cold start points toward oil pressure and VVT phaser response; one that appears under load or across the full RPM range points more toward actual chain stretch. Many scan tools also report a “bank 1 cam/crank correlation” or “cam/crank timing deviation” PID in degrees — if yours does, a deviation in the low single digits is borderline, while double digits is a clear mechanical fault.
Symptoms You May Notice Alongside the Code
P0016 sometimes sets with no driveability change at all, which is part of why people are tempted to just clear it and move on. When symptoms are present, the most common are a rattling or chain-slap noise for a second or two on cold startup, a rough or uneven idle, reduced power or hesitation under acceleration, and occasionally a misfire code (P0300 or a cylinder-specific P030X) alongside it, because timing that has drifted far enough affects combustion on top of the correlation check itself. A no-start or hard-start condition is possible but rare with P0016 alone — that is more typical of a chain that has actually skipped a tooth rather than one that has simply stretched.
1. Stretched Timing Chain
Timing chains do not snap without warning in most cases — they stretch gradually as the pins and rollers wear, which lets the chain ride looser on its sprockets. That slack shows up first as a small timing deviation the ECM tolerates, then a larger one it flags as P0016 once the chain has stretched enough to shift cam timing outside the correlation window. Chain stretch is measured in percentage elongation; most manufacturers consider anything over roughly 0.5–1% worn enough to replace. It is the single most common cause of a genuine (not intermittent) P0016 on engines with 80,000–150,000 miles of use, especially on engines with a documented history of chain wear like GM’s 2.4L Ecotec, Chrysler’s 3.6L Pentastar, and several Ford EcoBoost 4-cylinders.
2. Worn Chain Guides or a Weak Tensioner
The chain itself can still be within spec while the plastic guides that keep it aligned, or the tensioner that keeps it under proper preload, have failed. A worn guide lets the chain flex under load, which shows up as a bigger timing deviation at higher RPM than at idle — the opposite pattern from a VVT phaser problem, which tends to be worse at idle. A tensioner that has lost hydraulic pressure (from a stuck check valve or worn piston) allows slack to develop even with a chain that measures fine, which is why a shop checking for this cause pulls the timing cover rather than just measuring chain stretch in isolation.
3. Failed VVT Phaser or Cam Actuator
Variable valve timing engines control cam phase with an oil-pressure-actuated phaser (also called an actuator) mounted on the camshaft, commanded by a VVT solenoid or oil control valve. A worn phaser develops internal play — the same mechanism that causes the classic “VVT rattle” for a second or two right at cold startup, before oil pressure builds enough to take up the slack. That same play is exactly what a correlation check is built to catch: the phaser physically cannot hold the commanded cam angle precisely, so the crank/cam relationship wanders outside tolerance. This is a distinct part from the timing chain and does not always mean the chain is also worn, though on high-mileage engines both frequently show wear together.
4. Low or Contaminated Oil Pressure to the Phaser
A phaser that is mechanically fine can still misbehave if it does not get clean oil at the right pressure fast enough. Low oil level, an overdue oil change with sludge partially blocking the feed galley, the wrong viscosity for the season, or a weak oil pump can all delay how quickly the phaser reaches its commanded position after startup or an RPM change, and the ECM’s correlation check has a limited window to tolerate that lag before it flags a code. This is worth ruling out early because it is the cheapest possible cause — a fresh oil change with the correct spec can resolve a P0016 that has nothing mechanically wrong with it.
5. Clogged VVT Oil Control Valve Filter Screen
Most VVT oil control valves (also called cam phaser solenoids) have a small mesh filter screen on the oil feed to protect the valve from debris. Over time that screen collects sludge and metal particulate, which restricts oil flow to the phaser even when overall engine oil pressure is normal. This produces the same symptom as low oil pressure — a phaser that responds too slowly — but the fix is different: the screen or the whole oil control valve needs to be cleaned or replaced, not the oil pump. This cause is common enough on engines that have gone long stretches between oil changes that it is worth checking before assuming the phaser itself has failed.
6. Skipped Timing Chain Tooth
If the chain has actually jumped a tooth on a sprocket — from severe wear, oil starvation, or a chain that was installed slightly loose during a prior repair — the crank/cam relationship shifts by a fixed, large amount rather than drifting gradually. This produces a much larger correlation deviation than ordinary stretch, often paired with a rough idle, a misfire code, and sometimes a no-start. This is the version of P0016 that carries real risk on an interference engine (where the pistons and valves occupy the same space at different points in the rotation), because a chain that has already jumped once can jump again and cause valve-to-piston contact. A chain that has skipped enough to disrupt combustion can also produce audible backfiring through the exhaust, since cylinders firing out of sequence with valve position send unburned fuel into a hot exhaust system.
7. Camshaft or Crankshaft Sensor Fault
The least likely cause, but real: a sensor with a degrading signal — from a widening air gap, a cracked reluctor tooth, or a connector with intermittent contact — can produce a signal that is technically present but distorted enough to throw off the correlation calculation even though the mechanical timing is fine. This is more plausible when the code is intermittent, comes and goes with engine temperature, or clears and does not return for a long time after a battery disconnect. A sensor fault causing P0016 without also setting a P0335 or P0340 circuit code is uncommon but not impossible, since a degraded-but-present signal can pass the circuit check while still failing the correlation check. If you are trying to work out whether a specific sensor or the mechanical timing is at fault, see our comparison of bad crankshaft sensor vs. bad camshaft sensor symptoms for the tests that separate the two.
Diagnostic Order
Start cheap and work toward invasive. Check the oil level and condition first — if it is low, dark, or overdue, address that and clear the code before doing anything else, since it costs nothing to rule out. Next, with a scan tool that supports live data, compare commanded versus actual cam timing angle at idle and at 2,000–2,500 RPM; a phaser or oil-delivery problem typically shows a larger gap at idle that narrows as RPM and oil pressure rise, while a stretched chain or worn guides typically shows a gap that stays roughly proportional or worsens with load. Listen specifically for the one-to-three-second startup rattle that identifies phaser wear. If mechanical inspection is warranted, a technician will pull the valve cover or timing cover to physically measure chain slack and inspect the guides, which is the only way to confirm stretch versus a phaser-only problem. Do not replace the crank or cam sensor as a first guess on this code — save that for after mechanical causes are ruled out, since sensors are the least statistically likely cause of a correlation fault.
Repair Cost
A full timing chain kit — chain, guides, tensioner, and sprockets replaced together, which is the correct way to do this repair rather than replacing the chain alone — typically runs $400 to $1,800 depending on the engine layout; a V6 or V8 with dual overhead cams and multiple phasers costs meaningfully more in labor than a simple inline-four. A single VVT phaser replaced on its own, when the chain and guides test fine, runs $250 to $700 per phaser including parts and labor. An oil control valve or its filter screen is a comparatively small repair at $60 to $250. At the low end, an overdue oil change that resolves a low-oil-pressure cause costs under $100. Sensor replacement, when it genuinely is the cause, is usually $80 to $250.
Can You Keep Driving With It?
A P0016 with no noise and no drivability symptoms, on an engine with clean, correct-level oil, is reasonable to drive on for a short period while you arrange diagnosis — the underlying deviation is small enough that the ECM is flagging a trend rather than an emergency. That changes the moment a startup rattle, rough idle, misfire, or noticeable power loss shows up alongside the code, because those are the signs of either advancing chain slack or a phaser that has degraded further, and both get worse under continued use rather than better. On an interference engine specifically, a P0016 that is accompanied by any rattling noise is worth having checked within days, not weeks — the cost difference between replacing a stretched chain proactively and replacing bent valves after a skipped tooth is not small. If the code is accompanied by a check engine light that starts flashing, or the engine begins to misfire noticeably, stop driving and have the vehicle towed rather than risk it.
Related Codes
P0016 is one of a family of correlation and circuit codes that are easy to confuse. P0017 is the equivalent correlation fault for bank 1, sensor B (typically the exhaust camshaft on a dual-VVT engine), so a vehicle throwing both P0016 and P0017 together points strongly toward a shared cause — low oil pressure or a stretched chain affecting both phasers — rather than two independent sensor failures. P0335 and P0340 are the underlying circuit codes for the crank and cam sensors respectively; if one of those sets alongside P0016, diagnose the circuit fault first, since a genuinely broken sensor signal can also throw off the correlation check as a side effect. A vehicle that sets P0016 without any circuit code is the cleaner case described throughout this article — both sensors are working, and the timing relationship itself has drifted.
What does P0016 mean?
The engine control module compared the crankshaft position sensor signal against the bank 1, sensor A camshaft position sensor signal and found the timing relationship between them outside the acceptable range. Unlike a circuit code, both sensors are sending valid signals — the physical timing between crank and cam has drifted.
How much does it cost to fix a P0016 code?
A full timing chain kit (chain, guides, tensioner) runs $400 to $1,800 depending on engine layout. A single VVT phaser replaced alone is $250 to $700. An oil control valve or its filter screen is $60 to $250. If low or overdue oil is the cause, a proper oil change can resolve it for under $100.
Is it safe to drive with a P0016 code?
Short term, if there is no rattling noise, rough idle, or misfire, it is reasonable to keep driving while you arrange diagnosis. If any startup rattle, rough running, or power loss appears alongside the code, have it checked promptly — those signs point to advancing chain slack or phaser wear, which get worse with continued driving and carry real risk on interference engines.
Will clearing a P0016 code make it come back?
If the underlying cause is mechanical — a stretched chain, worn guides, or a failed phaser — clearing the code with a scan tool resets the light temporarily but the code returns once the correlation check runs again, usually within one drive cycle. If the cause was low or degraded oil, a proper oil change can resolve it permanently.
Can I fix a P0016 code myself?
Checking and changing the oil, and inspecting for an obvious loose connector on the cam or crank sensor, are reasonable DIY steps. Timing chain, guide, tensioner, and phaser replacement require removing the timing cover and setting cam-to-crank timing precisely, which is beyond typical DIY tools and carries real risk of engine damage if done incorrectly — this repair is usually left to a shop.
What is the difference between P0016 and P0335?
P0335 means the module received no valid signal at all from the crankshaft position sensor — a circuit fault. P0016 means both the crank and cam sensors are sending valid signals, but the timing relationship between them has drifted outside tolerance — almost always a mechanical fault like chain stretch or a worn VVT phaser rather than a sensor or wiring problem.
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