Code Definition

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

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0021

P0021 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0021 is stored, the module has detected a plausibility fault — the measured value is in the electrical range but is not consistent with expected operating behaviour; and a bank-specific fault, meaning it applies only to one cylinder bank of a multi-bank engine.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0021 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The Engine Control Module (ECM) uses the Bank 2 Camshaft Position A (intake) sensor to monitor where the intake camshaft sits relative to crankshaft rotation, and commands the Variable Valve Timing (VVT) phaser to advance or retard the cam through an oil control valve. DTC P0021 is set when the ECM measures that actual intake cam position on Bank 2 is more advanced than the commanded value, or that the phaser remains stuck in an advanced position and will not return to base timing on command. The VVT phaser is a hydraulic actuator mounted on the nose of the camshaft that uses pressurised engin...

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