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

P0021 means the intake camshaft on bank 2 is positioned more advanced than the ECU commanded it to be. The variable valve timing system on bank 2 is not responding correctly, typically due to oil flow issues, a faulty bank 2 VVT solenoid, a stretched timing chain, or a worn cam phaser. The code only appears on V6, V8, V10, and V12 engines.

P0021 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0021 and illuminates the check engine light.

If your vehicle has triggered P0021, you may notice one or more of these symptoms:

• Check engine light illuminated
• Rough or unstable idle, possible stalling
• Hard starting, especially when warm
• Rattling noise from the front of the engine on cold start
• Reduced fuel economy
• Failed emissions test

Here are the most common causes of P0021, ranked by how likely they are to be the culprit:

Generally yes, for short-term driving. Short trips to a workshop are acceptable, but the engine may stall, idle roughly, or hesitate. P0021 is a bank 2 fault, so your engine is a V6 or larger. Continued driving with timing chain damage on a V-engine risks expensive valve damage on interference designs.

Follow these steps to pinpoint the root cause of P0021:

1. Check engine oil level and condition. Low, dirty, or wrong-viscosity oil is the most common cause of P0021. Use only the manufacturer-specified oil approval and change if overdue
2. Use a scan tool to monitor live cam phasing data on bank 2. Compare the actual versus commanded intake cam advance angle. Deviations over 5 to 10 degrees confirm a real timing fault
3. Locate the bank 2 intake VVT solenoid (typically on the bank 2 valve cover or front of the bank 2 cylinder head). Measure resistance (6 to 13 ohms typical) and inspect the mesh filter screen for sludge
4. Listen for cold-start rattle from the bank 2 side of the engine. A timing chain rattle on bank 2 specifically points to chain or tensioner wear on that bank
5. If the oil and solenoid are good, suspect timing chain or guide wear. A workshop will need to remove the bank 2 valve cover for inspection, or check timing chain wear with a service tool

Repair costs for P0021 vary depending on the root cause and your vehicle. Here are typical estimates:

P0021 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:

These codes are often seen alongside P0021 or indicate related issues: