P0021
A Camshaft Timing Over-Advanced (Bank 2)
The engine computer has found that the intake camshaft on bank 2 is too far advanced or not moving as expected. This can be caused by dirty oil, a bad oil control valve, a stuck cam phaser, or wiring problems.
- SEV
- 3/5
- DRIVE
- CAUTION
- DIY
- $20–$300
- SHOP
- $150–$900
Quick answer
AI-CITATION READYWhat it means
Can you drive with it?
Most common causes
- Dirty, low, wrong viscosity, or degraded engine oil
- Faulty oil control valve / variable valve timing solenoid on bank 2
- Stuck or worn cam phaser on bank 2
Typical repair cost
DIY usually runs $20–$300. Typical shop repair lands around $150–$900, depending on the root cause.
01 / Definition
P0021 means the engine control module detected that the intake camshaft timing on bank 2 is more advanced than the commanded position, or the system is not responding correctly. This is usually a variable valve timing problem involving oil pressure, the oil control solenoid, cam phaser operation, timing components, or sensor feedback. On some vehicles, the fault can be intermittent and set only under certain engine speeds or oil temperatures.
02 / Drive status
With caution. The vehicle may still run, but it can idle poorly, lose power, or run rough. Avoid hard driving and get it diagnosed soon because continued driving can worsen engine damage or drivability problems.
03 / Symptoms
- Check engine light
- Rough idle
- Poor acceleration
- Reduced fuel economy
- Hard starting
- Engine hesitation
- Engine running rough at certain speeds
- Possible rattling noise from timing area
04 / Causes
| 1 | Dirty, low, wrong viscosity, or degraded engine oil | high |
|---|---|---|
| 2 | Faulty oil control valve / variable valve timing solenoid on bank 2 | high |
| 3 | Stuck or worn cam phaser on bank 2 | medium |
| 4 | Timing chain stretched or timing components worn out | medium |
| 5 | Blocked oil passages or low engine oil pressure | medium |
| 6 | Wiring, connector, or PCM control issue to the cam timing system | low |
| 7 | Faulty camshaft position sensor or crankshaft position sensor data issue | low |
05 / Diagnostic sequence
- 01Check engine oil level, condition, and correct viscosity.
- 02Inspect for related codes such as camshaft sensor, crankshaft sensor, or oil control solenoid codes.
- 03Inspect wiring and connectors at the bank 2 cam timing solenoid and cam sensor.
- 04Command or test the bank 2 variable valve timing solenoid with a scan tool if available.
- 05Check for oil contamination, sludge, or restricted oil passages.
- 06Verify camshaft timing actual vs commanded with live scan data.
- 07Test oil pressure if the system response is still incorrect.
- 08Inspect timing chain, cam phaser, and mechanical timing alignment if electrical and oil checks pass.
06 / Repairs
| 1 | Change engine oil and filter with the correct specification oil if oil is dirty, low, or incorrect. | $35–$120 |
|---|---|---|
| 2 | Clean or replace the bank 2 variable valve timing solenoid / oil control valve. | $50–$250 |
| 3 | Repair damaged wiring, connectors, or poor grounds to the cam timing system. | $20–$200 |
| 4 | Replace a stuck or worn cam phaser if it fails testing. | $250–$900 |
| 5 | Repair timing chain, guides, tensioner, or related mechanical timing components if worn or out of alignment. | $500–$2,000 |
07 / Related codes
08 / FAQ
Is P0021 serious?
It is moderately serious. The engine may still run, but performance and reliability can suffer, and the problem can get worse if the oil or timing system issue is ignored.
Can low oil cause P0021?
Yes. Low oil level, dirty oil, or the wrong oil viscosity can prevent the variable valve timing system from working correctly.
Will an oil change fix P0021?
Sometimes. If the issue is caused by dirty, old, or incorrect oil, an oil change may solve it. If the solenoid, phaser, or timing parts are failing, more repair is needed.
Which bank is bank 2?
Bank 2 is the side of the engine that does not contain cylinder number 1. The exact location depends on the engine design.
09 / Source and method
- DATA BASIS
- OBD-II REFERENCE + OBD2.HELP
- METHOD
- STATIC VALIDATION
- SAFETY
- INFORMATIONAL
This page combines OBD-II diagnostic reference data with OBD2.help generated diagnostic guidance for code meaning, likely causes, and repair direction.
Publishing uses deterministic schema and build validation, plus manual spot checks on representative pages before release.
Safety-critical diagnosis and repairs should be confirmed with a qualified mechanic, especially when the vehicle is misfiring, overheating, or losing power.