P0021 — “Camshaft Position (CMP); Intake/Left/Front Bank 2 Timing Over-Advanced/System Performance” #

The label for this Diagnostic Trouble Code (DTC) may vary depending on the vehicle manufacturer (OEM). Always refer to your service manual for the exact wording.

Known label variations:

• P0021 – “A” Camshaft Position Timing Over-Advanced or System Performance (Bank 2) — Toyota/Lexus
• P0021 – Intake Camshaft Position Timing – Over-Advanced (Bank 2) — Nissan/Infiniti
• P0021 – Camshaft Position – Timing Over-Advanced or System Performance (Bank 2) — Ford
• P0021 – Camshaft Position Sensor ‘A’ Timing Over Advanced (Bank 2) — Subaru

Summary of code P0021 #

P0021 is an OBD-II generic powertrain code indicating a problem with the intake camshaft timing on Bank 2 (the side of the engine with cylinder 2, 4, 6, etc. in a V-engine). This code is triggered when the Engine Control Module (ECM) detects that the camshaft position is more advanced than commanded, which means the camshaft timing is ahead of where it should be according to engine conditions. This timing discrepancy can affect engine performance, emissions, and drivability. Variable Valve Timing (VVT) or Variable Camshaft Timing (VCT) systems are typically involved, and the issue can range from a minor oil flow problem to a faulty actuator or sensor. Prompt investigation is recommended to prevent potential engine damage.

Common symptoms for trouble code P0021 #

When P0021 is stored, the vehicle may exhibit noticeable symptoms or, in some cases, none at all. However, most drivers will experience one or more of the following:

• Illuminated Check Engine Light (CEL) on the dashboard
• Rough engine idle, especially when cold
• Hesitation, stumble, or lack of power during acceleration
• Poor fuel economy
• Engine may run rich or lean intermittently
• Hard starting or extended cranking
• Possible engine knocking or rattling noises

Most likely causes for code P0021 #

There are several potential causes for P0021. Some are more common than others, and a systematic diagnosis is essential to avoid unnecessary repairs. Typical causes include:

1. Low or dirty engine oil (oil flow is critical for VVT operation)
2. Faulty Variable Valve Timing (VVT) solenoid/actuator for intake camshaft on Bank 2
3. Incorrect camshaft timing due to stretched or misaligned timing chain/belt
4. Contaminated or blocked oil passages to the VVT system
5. Faulty camshaft position sensor (CMP) on Bank 2
6. Wiring issues (damaged connectors or harness between ECM and VVT/CMP components)
7. Faulty Engine Control Module (ECM) (rare)

Step-by-step diagnosis for code P0021 #

A methodical approach is essential. Rushing can lead to misdiagnosis and wasted time or money. Use this checklist as a guide:

• 1. Check the engine oil level and condition. Top up if low; change if dirty or overdue.
• 2. Scan for other codes. Address any related oil pressure, camshaft, or crankshaft codes first.
• 3. Inspect the VVT solenoid/actuator on Bank 2. Look for signs of blockage, wear, or electrical faults.
• 4. Test the camshaft position sensor (CMP) on Bank 2. Use a scan tool to monitor live data for erratic or implausible readings.
• 5. Check wiring and connectors. Look for corrosion, fraying, or loose pins between the ECM, VVT solenoid, and CMP sensor.
• 6. Inspect the timing chain or belt. If mileage is high or symptoms persist, check for slack, misalignment, or stretch.
• 7. Perform an oil pressure test. Low oil pressure may affect VVT operation.
• 8. If all else fails, consult OEM service data for advanced diagnostics, including actuator function tests or ECM replacement.