OBD2 Fault Code Library

Free lookup for thousands of OBD2 trouble codes: filter by family, read short meanings, and open deeper articles. Desktop ELM327 scanner with live data and AI guidance.

OBD2 symptoms

Look up diagnostic trouble codes by what the car is doing: misfire, overheating, rough idle, a check engine light, and other common symptoms.

P051B — Crankcase Pressure Sensor Circuit Range/Performance (P051B): a powertrain (engine/transmission) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by corroded, loose or damaged connector, control module driver fault, faulty sensor or actuator of the affected circuit.
P051C — OBD2 code P051C flags a problem with the sensor and actuator circuits (crankcase pressure sensor circuit low). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, corroded, loose or damaged connector, poor ground connection.
P051D — P051D — Crankcase Pressure Sensor Circuit High. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: poor ground connection, corroded, loose or damaged connector, control module driver fault.
P051E — Crankcase Pressure Sensor Circuit Intermittent/Erratic (P051E): a powertrain (engine/transmission) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit, control module driver fault.
P051F — Positive Crankcase Ventilation Filter Restriction (P051F): a powertrain (engine/transmission) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by control module driver fault, faulty sensor or actuator of the affected circuit, poor ground connection.
P0520 — P0520 — Engine Oil Pressure Sensor/Switch Circuit Malfunction. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: control module driver fault, poor ground connection, faulty sensor or actuator of the affected circuit.
P0521 — P0521 — Engine Oil Pressure Sensor/Switch Circuit Range/Performance. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: control module driver fault, corroded, loose or damaged connector, poor ground connection.
P0522 — OBD2 code P0522 flags a problem with the sensor and actuator circuits (engine oil pressure sensor/switch circuit low voltage). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, open or shorted wiring in the circuit, corroded, loose or damaged connector.
P0523 — OBD2 code P0523 flags a problem with the sensor and actuator circuits (engine oil pressure sensor/switch circuit high voltage). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, open or shorted wiring in the circuit, faulty sensor or actuator of the affected circuit.
P0524 — OBD2 code P0524 flags a problem with the sensor and actuator circuits (engine oil pressure too low). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, poor ground connection, blown fuse feeding the circuit.
P0525 — OBD2 code P0525 flags a problem with the sensor and actuator circuits (cruise control servo control circuit range/performance). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, blown fuse feeding the circuit, open or shorted wiring in the circuit.
P0526 — Fan Speed Sensor Circuit (P0526): a powertrain (engine/transmission) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by corroded, loose or damaged connector, poor ground connection, open or shorted wiring in the circuit.
P0527 — P0527 — Fan Speed Sensor Circuit Range/Performance. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: open or shorted wiring in the circuit, poor ground connection, corroded, loose or damaged connector.
P0528 — P0528 — Fan Speed Sensor Circuit No Signal. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: corroded, loose or damaged connector, poor ground connection, open or shorted wiring in the circuit.
P0529 — OBD2 code P0529 flags a problem with the sensor and actuator circuits (fan speed sensor circuit intermittent). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit, corroded, loose or damaged connector.
P052A — P052A — Cold Start "A" Camshaft Position Timing Over-Advanced Bank 1. A fault in the camshaft position and variable valve timing. Short, gentle driving to a shop is usually possible. Typical causes: low or dirty engine oil affecting VVT, damaged sensor wiring or reluctor ring, worn cam phaser.
P052B — OBD2 code P052B flags a problem with the camshaft position and variable valve timing (cold start "A" camshaft position timing over-retarded bank 1). Short, gentle driving to a shop is usually possible. Common culprits: damaged sensor wiring or reluctor ring, worn cam phaser, stuck or clogged VVT oil control valve (OCV).
P052C — OBD2 code P052C flags a problem with the camshaft position and variable valve timing (cold start "A" camshaft position timing over-advanced bank 2). Short, gentle driving to a shop is usually possible. Common culprits: low or dirty engine oil affecting VVT, worn timing chain/belt or jumped timing, damaged sensor wiring or reluctor ring.
P052D — OBD2 code P052D flags a problem with the camshaft position and variable valve timing (cold start "A" camshaft position timing over-retarded bank 2). Short, gentle driving to a shop is usually possible. Common culprits: worn timing chain/belt or jumped timing, worn cam phaser, stuck or clogged VVT oil control valve (OCV).
P052E — Positive Crankcase Ventilation Regulator Valve Performance (P052E): a powertrain (engine/transmission) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by faulty sensor or actuator of the affected circuit, corroded, loose or damaged connector, poor ground connection.
P0530 — OBD2 code P0530 flags a problem with the sensor and actuator circuits (A/C refrigerant pressure sensor "A" circuit). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit.
P0531 — P0531 — A/C Refrigerant Pressure Sensor "A" Circuit Range/Performance. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: poor ground connection, control module driver fault, faulty sensor or actuator of the affected circuit.
P0532 — OBD2 code P0532 flags a problem with the sensor and actuator circuits (A/C refrigerant pressure sensor "A" circuit low). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, open or shorted wiring in the circuit, poor ground connection.
P0533 — OBD2 code P0533 flags a problem with the sensor and actuator circuits (A/C refrigerant pressure sensor "A" circuit high). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, poor ground connection, control module driver fault.