P0021
A Camshaft Position - Timing Over-Advanced or System Performance Bank 2
Variable valve timing
Generic OBD-II
High
What it means
P0021 means the variable valve timing on bank 2 is over-advanced, or the cam timing isn't responding the way the ECM commands. The system runs on oil pressure through a solenoid and phaser, so low or dirty oil is a frequent cause. Expect rough running and reduced power until it's sorted.
High
Can I keep driving? Limp along only — the engine may run rough or stall and timing faults can stress the valvetrain, so drive as little as possible until it's fixed.
Common symptoms
What you'll notice
- Check-engine light on
- Rough idle, hesitation, or occasional stalling
- Reduced power and sluggish acceleration
- Rattle or whine from the front of the engine on some vehicles
Common causes
Most likely first
- Low or dirty engine oil — the most common trigger; the VVT phaser runs on oil pressureLikely
- Stuck or clogged camshaft oil-control (VVT) solenoid on bank 2Common
- Faulty camshaft position sensor or wiringCommon
- Worn camshaft phaser/actuator on bank 2Less often
- Stretched timing chain or jumped timing causing the cam to sit over-advancedLess often
- Rarely, a faulty ECMLess often
How to diagnose & fix
Work through it in order
- Check the oil level and condition first — top up or change the oil with the correct grade if it's low, dirty, or overdue.
- Read freeze-frame data and inspect the bank 2 VVT solenoid; remove and clean it, checking for sludge and debris.
- Test the camshaft position sensor and its wiring for the correct signal.
- If oil and solenoid check out, inspect the phaser and verify timing-chain condition and cam/crank correlation.
- Clear the code and re-test after each step to confirm the fix.
FAQ
Quick answers
Is it safe to drive with P0021?+
Only briefly. The engine may run rough or stall, and a real timing fault can stress the valvetrain. Get it looked at promptly rather than driving on it.
Can I just clear P0021?+
It will come straight back unless the cause is fixed. Because low or dirty oil is the usual trigger, an oil change is worth doing before clearing.
Related codes
Often seen with P0021
Read & clear P0021 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX