P0021: 'A' Camshaft Position - Timing Over-Advanced or System Performance (Bank 2)
Severity: medium
What it means: The 'A' camshaft on bank 2 is too far advanced or not following command compared with what the engine computer commanded through variable valve timing.
Safe to drive? Short trips are usually OK, but have it checked soon. Timing problems can get worse and, on some engines, point to chain wear.
Common symptoms
- Check-engine light
- Rough idle or stalling
- Reduced power
- Rattle at startup on some engines
Likely causes, ranked
- Low or dirty engine oilDIY
- Sticking oil control (VVT) solenoidDIY
- Worn or stretched timing chain, or a faulty cam phaserShop
- Wiring faultShop
What it means: The 'A' camshaft on bank 2 is too far advanced or not following command compared with what the engine computer commanded through variable valve timing.
Severity: Medium. Safe to drive? Short trips are usually OK, but have it checked soon. Timing problems can get worse and, on some engines, point to chain wear.
DIY or shop?
Check the oil level and change the oil first. Chain and phaser work is a shop job.
Before you replace parts
- Read all stored codes and freeze-frame data. Fix misfire, fuel or sensor codes before chasing emissions codes.
- Check the simple things first: connectors, vacuum hoses, fluid levels and the gas cap.
- Clear the code only after a repair, then confirm it stays off after a few drives.
- Check your VIN for recalls and service bulletins.
Safety / mechanic note
Verify with a mechanic if you notice drivability changes, warning lights or overheating. A code points to a circuit or system, not always a specific part.