P0021 means Intake Camshaft Position Timing Over-Advanced or System Performance (Bank 2). The bank 2 intake camshaft is more advanced than the computer commanded, or the timing system is not responding as expected. It is a generic OBD-II code, so the definition is the same on any make, but the most likely cause varies by engine; confirm with a scan tool and the service information for your vehicle before buying parts.
What P0021 means
The engine computer uses the crankshaft position sensor to know engine speed and piston position, and the camshaft sensors to know which stroke each cylinder is on. On engines with variable valve timing, oil-driven cam phasers rotate the camshafts relative to the crankshaft under the control of solenoids. Timing codes come from a sensor that cannot be read, or from a measured cam angle that does not match the commanded one, so oil level and condition, sensor signals and mechanical timing all need checking.
P0021 symptoms
- Check engine light
- Rough idle or stalling on some engines
- Reduced power or poor fuel economy
Common causes of P0021
- Low or dirty oil, or the wrong oil viscosity
- Sticking cam timing solenoid
- Worn cam phaser
- Stretched timing chain
How to diagnose P0021
- Check oil level and condition, and confirm the oil viscosity matches the specification
- Check the bank 2 intake cam solenoid connector and wiring
- Watch commanded vs actual cam angle on a scan tool
- Test the solenoid’s resistance and operation with a bidirectional scan tool
Can you drive with P0021?
Usually short term; fix soon, because some causes (low oil, chain stretch) get worse.
P0021 tips
Codes for the same direction on both banks (for example P0011 and P0021) point to something shared, such as oil condition or timing chain stretch, rather than one solenoid.
Will P0021 clear itself?
If the fault stops, the computer turns off the check engine light by itself after several drive cycles without seeing it again, and the code stays in memory as history for a while. Clearing P0021 with a scan tool after a repair is fine, but if the cause is still there the code returns, sometimes within one drive. Disconnecting the battery also clears codes on most vehicles, but it erases learned fuel trims and idle settings as well.
Related codes
| Code | Meaning |
|---|---|
| P0020 | Intake Camshaft Position Actuator Circuit (Bank 2) |
| P0022 | Intake Camshaft Position Timing Over-Retarded (Bank 2) |
| P0018 | Crankshaft Position – Camshaft Position Correlation (Bank 2 Sensor A) |
Guides that help
When it is more than a sensor
If a stretched chain has already jumped time and damaged valves, or low oil pressure has worn the engine, a repair can cost more than a replacement; see engine replacement cost and compare engines by code on our engines page.
More guides: bad cam phaser symptoms.
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