Intake Camshaft Position Timing - Over-Advanced (Bank 2)
The intake camshaft on Bank 2 is rotating too far ahead of where it should be, like a dancer stepping out of sync with the music. This throws off the engine's valve timing and air-fuel mixture, causing performance issues.
The ECU monitors the camshaft position sensor (CMP) signal on Bank 2 and compares actual camshaft timing against the crankshaft position. When the intake cam advances beyond the maximum allowable threshold (typically 5-10 degrees), the ECU detects over-advancement and sets the fault code.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Intake Cam Timing (Bank 2) | 0 to +5 degrees BTDC | >+5 to +10 degrees BTDC (over-advanced) |
| CMP-to-CKP Correlation | Within ±2 degrees | Exceeds +5 degrees variance |
Code P0021 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0021 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.