P0021: "A" Camshaft Position – Timing Over-Advanced Or System Performance (Bank 2)
The "A" camshaft on bank 2 is earlier than commanded or does not follow the commanded position.
High risk
Usually drivable, but running may suffer. Have it checked soon.
Short answer · Can I keep driving with P0021?
Usually yes. The engine may idle roughly or lose some power. Check the oil and have the timing system checked soon.
What does P0021 mean?
Code P0021 is the bank 2 version of P0011. It appears on V and boxer engines when the bank 2 intake camshaft adjuster does not reach or hold its target.
What the car does when the code is set
The check engine light comes on. The engine may idle roughly, lose power or use more fuel, because the valve timing is not where the engine control unit wants it. Some engines lock the camshaft adjuster in a default position.
How the system works
Variable valve timing lets the engine change when the valves open and close. A camshaft adjuster (phaser) on the end of the camshaft turns it a few degrees relative to the sprocket, driven by engine oil that an oil control valve directs to one side or the other. The engine control unit commands a target angle, then measures the real angle by comparing the camshaft and crankshaft sensor signals. If the measured angle differs from the target for too long, or the two signals are out of their normal relationship, it stores a code.
Common symptoms
Possible causes
Listed without ranking. The cause on your car depends on make, engine and mileage — see the maker notes below.
- Low or dirty engine oilVariable valve timing uses oil pressure; low level or old oil makes it slow.
- Faulty oil control valveThe solenoid that directs oil to the camshaft adjuster sticks.
- Worn camshaft adjusterThe adjuster (phaser) no longer holds its position.
- Stretched timing chain or jumped beltCamshaft and crankshaft are no longer in the correct relation.
- Sensor or reluctor wheel problemA faulty position sensor or damaged trigger wheel.
How it is diagnosed
- Check oil level and conditionTop up or change the oil with the specified grade first. This alone sometimes clears the fault.
- Compare desired and actual camshaft positionWith live data, watch whether the camshaft follows the commanded angle at idle and at higher revs.
- Test the oil control valveCheck its resistance and operation, and look for debris in its screen.
- Check the timingIf the readings point to a stretched chain, the workshop checks the timing marks or measures the offset.A worn timing chain can jump teeth and damage the engine. Do not delay the diagnosis.
Questions about P0021
Where is bank 2?
Bank 2 is the side of the engine without cylinder 1. Straight engines have only bank 1.
Can low oil cause this code?
Yes. Valve timing control depends on oil pressure, so low or old oil is one of the first things to check.