P0021 Intake Camshaft Position Timing Over-Advanced Bank 2

P0021 means the intake camshaft timing on bank 2 is more advanced than expected. The cam may be stuck advanced, slow to return, or reported incorrectly.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not treat P0021 as only a cam sensor problem; oil control, actuator sticking, and mechanical timing can all create this result.

Symptoms of P0021

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0021

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Verify oil level, oil viscosity, contamination, and service history before replacing variable valve timing parts.
Compare commanded and actual bank 2 intake cam angle at idle and during a controlled RPM change.
Inspect the actuator solenoid, phaser operation, timing-chain or belt condition, and bank-specific cam/crank correlation data.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.