P0021 Code – "A" Camshaft Position Timing Over-Advanced or System Performance (Bank 2)

The P0021 diagnostic trouble code (DTC) is a generic OBD-II powertrain code that indicates the engine control module (ECM) has detected that the intake camshaft timing on Bank 2 is more advanced than expected or that the Variable Valve Timing (VVT) system is not performing correctly.

What Does P0021 Mean?

P0021 stands for "A" Camshaft Position Timing Over-Advanced or System Performance (Bank 2). This means the intake camshaft on Bank 2 has advanced beyond the manufacturer's specified limit or the VVT system is unable to control camshaft timing correctly.

Symptoms of P0021

• Check Engine Light illuminated.
• Rough idle.
• Reduced engine performance.
• Poor acceleration.
• Hard starting.
• Increased fuel consumption.
• Engine hesitation or stalling.

Common Causes

• Dirty or low engine oil.
• Faulty VVT oil control solenoid.
• Blocked oil passages.
• Stretched or incorrectly timed timing chain.
• Faulty camshaft position sensor.
• Damaged wiring or poor electrical connections.
• Faulty VVT actuator.
• Faulty ECM (rare).

How to Diagnose P0021

1. Check engine oil level and condition.
2. Scan for additional diagnostic trouble codes.
3. Monitor live camshaft timing data.
4. Inspect and test the VVT oil control solenoid.
5. Inspect timing chain alignment.
6. Test the camshaft position sensor.
7. Inspect wiring and connectors.

How to Fix P0021

• Replace contaminated engine oil and filter.
• Replace the faulty VVT oil control solenoid.
• Clean blocked oil passages.
• Repair damaged wiring or connectors.
• Replace the camshaft position sensor if necessary.
• Repair or replace worn timing chain components.
• Replace the VVT actuator if defective.

Estimated Repair Cost

• Oil and filter change: $40–$120
• Camshaft position sensor: $80–$250
• VVT oil control solenoid: $150–$400
• Timing chain replacement: $800–$2,500+
• VVT actuator replacement: $300–$900

Note: Repair costs vary depending on the vehicle make, engine type, labor rates, and location.

Related Diagnostic Trouble Codes

• P0020
• P0022
• P0023
• P0024
• P0025

Can You Drive with P0021?

Driving with code P0021 is not recommended. Continued operation may reduce engine performance and could lead to severe engine damage if the timing chain or VVT system is faulty.

Conclusion

P0021 indicates that the intake camshaft timing on Bank 2 is excessively advanced or that the VVT system is not functioning properly. Common causes include dirty engine oil, VVT system failures, timing chain wear, or faulty sensors. Early diagnosis and repair help prevent costly engine damage.