P0012
Powertrain"A" Camshaft Position - Timing Over-Retarded (Bank 1)
The 'A' (intake) camshaft on bank 1 is more retarded than the ECU has commanded. The cam phaser isn't advancing the cam when the ECU asks it to.
ⓘ Information only. This page provides general educational information about fault code P0012. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0012 mean?
P0012 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: "A" Camshaft Position - Timing Over-Retarded (Bank 1).
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light
- • Rough idle, sometimes with a slight surge as the cam timing fails to track engine load
- • Slight hesitation under acceleration
- • Worse fuel economy, often noticeable on motorway runs
- • Sometimes a metallic rattle on cold start (chain wear on prone engines like BMW N47, Ford EcoBoost, VAG TSI)
Possible causes
Causes commonly associated with P0012, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. VVT solenoid stuck or carbon-fouled, the cheapest and most common cause
- 2. Low engine oil pressure, the cam phaser doesn't have hydraulic pressure to operate; check oil level first
- 3. Failed cam phaser, the variable mechanism inside the cam pulley has worn or jammed
- 4. Timing chain stretch on chain-stretch-prone engines, the chain has stretched enough that the cam can't be positioned correctly even with a healthy phaser
- 5. Wiring or connector issue at the solenoid
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Check oil level and condition first, a quick free check that catches a meaningful share of cases
- 2. Pull the VVT solenoid for the affected cam, clean it with carb cleaner, check the plunger moves freely with no carbon fouling
- 3. Read live data on actual vs commanded cam position; significant divergence under operating conditions confirms the system isn't responding
- 4. Listen for cold-start rattle, on chain-stretch engines a 5-10 second metallic rattle from the timing case is a strong indicator that the chain is the underlying cause
- 5. On chain-prone engines with high mileage, a stretched chain is the most likely culprit even if the solenoid swap is done; plan for chain replacement
Common questions about P0012
Difference between P0011 and P0012? +
Both are about cam A on bank 1. P0011 is over-advanced (the cam is more advanced than commanded). P0012 is over-retarded (less advanced than commanded). Same area of the system, opposite failure modes. Diagnostic approach is essentially identical: oil first, solenoid second, then phaser or chain.
Could a recent oil change have caused this? +
Sometimes yes, especially if the wrong viscosity or specification was used. Modern VVT engines need oils that meet specific manufacturer specs (BMW Longlife, VW 504/507, etc.). A standard '10W40 mineral' poured into a modern direct-injection engine starves the cam phasers and triggers VVT codes. Always check the oil spec on the cap or in the manual.
How urgent is this fix? +
Not urgent in the short term, drivability is fine. But VVT problems can progress to misfires and chain damage on prone engines, so don't ignore for long. If you're seeing a cold-start rattle or have a known chain-stretch engine, treat it as urgent because chain failure can cause catastrophic engine damage.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →