P0022
- Powertrain
- Generic (SAE)
- Emissions
Diagnose soon
A cam stuck retarded costs mid-range torque, fuel economy and emissions performance, and can idle roughly, but it does not destroy anything by itself. Severity rises immediately if the cause is low oil pressure or a stretched chain, since both are engine-threatening in their own right.
- Safe to drive
- Generally drivable in the short term. Stop and investigate immediately if oil pressure is low or you hear a startup chain rattle.
"A" Camshaft Position - Timing Over-Retarded (Bank 2)
The engine computer detected that the bank 2 'A' camshaft is sitting more retarded than it commanded — it asked for advance and did not get it. That is a measured position error, and several different faults can produce it.
The ECM commands camshaft phasing through a pulse-width-modulated oil control valve and reads actual cam angle back from the bank 2 camshaft position sensor referenced to the crankshaft signal. P0022 sets when the actual angle lags the commanded angle in the retard direction by more than the calibrated error for a set period. The usual mechanisms are a solenoid stuck closed or clogged, oil pressure or volume too low to stroke the phaser, varnish in the feed circuit, a worn phaser that leaks internally, or a chain stretched enough to sit the cam mechanically retarded.
How the car detected itWith enable conditions satisfied — engine running, oil temperature above a threshold (measured or modelled, since many engines infer it from coolant temperature and run time), stable rpm and load — the module commands a target cam angle, allows a settling period, then compares actual to target. If actual remains retarded of target beyond the allowed window through the confirmation period, the code sets. Some strategies also set it when the phaser cannot be moved off park at all. Error windows and settling times are calibrated per engine and are not a generic value.
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Generally drivable in the short term. Stop and investigate immediately if oil pressure is low or you hear a startup chain rattle.
- Urgency
- Diagnose soon
- Will it pass emissions
- No
- If ignored
- Continued loss of mid-range power and economy, and a guaranteed emissions test failure. If chain stretch is the cause, the chain can eventually jump timing, which on an interference engine means bent valves. If low oil pressure is the cause, the whole engine is running on inadequate lubrication while you wait.
- Check engine light
- Solid
- Clearing the light
- A completed drive cycle is normally required before the monitor re-runs and the light can clear.
- Power loss especially in mid-rpm range
- Possible rough idle or stalling
- Increased fuel consumption
Many vehicles show no symptom at all beyond the warning light. The absence of a symptom does not mean the fault is not real.
These are the causes this code can have. For the order to work through them in, see what to check first.
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | Oil control valve stuck (retard) | Very common | — |
| 2 | Cam phaser worn | Common | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
In order. Each of these is cheaper or faster than what follows it, and each one can make the rest unnecessary.
Oil level, condition and specified viscosity
This is a hydraulic actuator. Low level, degraded oil or too heavy a grade in cold weather stops the phaser moving before anything is actually broken.
Cold-start rattle from the bank 2 side
A one to three second rattle on startup points at a chain tensioner or stretched chain, which mechanically retards the cam and produces this code without any solenoid fault.
Freeze frame — coolant temperature, oil temperature where the vehicle reports it, and rpm when it set
Cold-only faults point at flow restriction and viscosity; hot-at-all-loads faults point at the valve, the phaser, or the chain. Many engines have no oil temperature sensor, in which case coolant temperature and run time are what you have to reason from.
Service history for oil change intervals
Skipped intervals are the direct route to varnish in the solenoid screen and the narrow phaser feed drillings.
Whether P0021 or bank 1 equivalents are also stored
Faults on both banks at once shift suspicion from a single solenoid to oil pressure, oil condition, or the pump.
Verify oil level, condition and grade first
Tools Dipstick, shop light
Check the level on level ground, inspect for sludge and varnish, and confirm the grade matches specification. If the oil is overdue, change oil and filter before further testing — otherwise every subsequent measurement is suspect.
ExpectedFull, clean, correct specified viscosity
Measure real oil pressure at operating temperature
Tools Mechanical oil pressure gauge and adapter, service information
Fit a mechanical gauge to the sender port and record pressure at idle and at a raised, steady rpm with the engine fully warm. A phaser will not stroke without adequate pressure and volume, and the dash lamp only warns at catastrophically low pressure. Target values are vehicle-specific.
Graph commanded versus actual cam angle on both banks
Tools Scan tool with live data graphing
Watch desired and actual cam position for bank 1 and bank 2 side by side at warm idle and on a light throttle sweep. Bank 2 lagging while bank 1 tracks correctly localizes the fault to that bank's hydraulics or mechanics. Both banks lagging points at oil supply. Confirm the engine's specified park value before judging the resting angle — it is not zero on every design.
ExpectedActual follows desired within the manufacturer's allowed error on both banks
Sweep the bank 2 phaser with bidirectional control
Tools Scan tool with bidirectional controls
Command the phaser through its range at a warm idle. No movement at all suggests a blocked screen, a stuck solenoid, or a restricted feed. Sluggish or partial movement suggests a worn phaser or marginal oil pressure.
ExpectedPrompt, full-range movement with a corresponding change in idle quality
Test the oil control valve and inspect its screen
Tools Digital multimeter, hand tools, 12 V bench supply, borescope
Check the winding resistance and the control circuit for opens or shorts, then remove the valve. Inspect the inlet screen for varnish and metal debris and stroke the spool on a bench supply. Look into the feed passage in the head or cover while the valve is out. Resistance specifications vary by vehicle.
ExpectedFree-moving spool, clean screen, unobstructed feed passage
Confirm the cam position signal is honest
Tools Two-channel lab scope, reference waveforms
Scope the bank 2 cam sensor against the crank sensor at idle and raised rpm. A weak, noisy or wrongly phased signal makes the module calculate a retarded angle regardless of where the cam actually is.
ExpectedClean, stable pulses holding a fixed phase relationship
Check mechanical timing and chain slack
Tools Cam locking tools, service information
If the hydraulics and electrics check out, verify the chain. Bring the engine to the manufacturer's reference position and compare marks or fit the specified locking tools, and assess tensioner extension. Excessive tensioner travel is a direct indicator of chain stretch. Procedures and specifications are engine-specific.
| Repair | Only after you confirm | Typical cost | Who |
|---|---|---|---|
| Oil and filter change with the correct specified viscosity | Oil found low, degraded or the wrong grade, and cam angle tracks command correctly afterwards | $60–$180 | DIY |
| Bank 2 'A' camshaft oil control valve and screen replacement | Screen found blocked or the spool found sticking on bench test, with oil pressure verified adequate | $150–$480 | DIY |
| VVT oil feed passage cleaning | Varnish or debris visible in the feed drilling with the solenoid removed, and a known-good solenoid still failing to move the phaser | $200–$700 | Hard |
| Bank 2 'A' camshaft phaser replacement | Oil pressure, feed passage and solenoid all verified good, but the phaser still moves sluggishly or not at all | $700–$2,500 | Shop |
| Timing chain, guide and tensioner replacement | Timing marks out of position, tensioner extended beyond its wear limit, or measured chain slack beyond specification | $1,200–$3,800 | Shop |
| Oil pump or pickup screen service | Mechanical gauge reads below specification at operating temperature with the correct oil in the sump | $700–$2,600 | Shop |
| Camshaft position sensor or wiring repair | Scope shows a degraded or wrongly phased cam signal with mechanical timing verified correct | $130–$420 | DIY |
The spread here is enormous because the same detected condition covers a $70 oil change and a $3,000 chain job. Pay for the diagnosis — $100 to $220 — rather than buying parts in order of price. Bank 2 access on a transverse V engine adds significant labour to any of these repairs.
- Buying a phaser before checking oil pressure. A phaser that cannot get oil behaves exactly like a phaser that has failed.
- Reinstalling a cleaned solenoid without addressing the oil that varnished it, then repeating the whole job later.
- Ignoring a brief cold-start rattle as 'normal for this engine'. It is a real signal that chain slack is contributing.
- Assuming bank 2 is the side furthest from the driver. Bank 2 simply does not contain cylinder 1, and its physical location varies by make.
- Using a heavier oil than specified to quiet a noisy engine, then wondering why the phaser will not move when cold.
- Camshaft Position Actuator
- Oil Control Valve
- Cam Phaser
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Reviewed
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