Code status
Needs verification
Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.
- System
- Fuel / Air
- Scope
- iso-sae-controlled-p0
- Standard
- SAE J2012 / ISO 15031-6
- Source
- legacy-import
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.
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 fault area. They may share the same verification status as the source database.