Code Definition

P0391 — Camshaft position sensor signal out of range Bank 2 sensor 2

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

About P0391

P0391 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 P0391 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; a bank-specific fault, meaning it applies only to one cylinder bank of a multi-bank engine; and a sensor-related fault — the reported value from the named sensor is out of spec.

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 P0391 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 ECM/PCM sets this code when it detects that the signal from the camshaft position sensor (CMP) on Bank 2, Sensor 2 is outside the expected range. This can occur due to incorrect timing correlation between the camshaft and crankshaft, signal voltage inconsistencies, or sensor circuit faults. The ECM relies on this signal for proper timing and fuel injection adjustments.

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