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.

• Engine misfire
• Engine overheating
• Rough idle
• Check engine light
• Poor fuel economy
• Hard starting
• Engine stalling
• Catalytic converter efficiency
• Oxygen sensor fault
• EVAP leak
• Thermostat not reaching temperature
• Lean air-fuel mixture
• Rich air-fuel mixture
• EGR flow fault
• Engine knock
• Charging system
• Throttle position
• Mass airflow sensor
• Turbo underboost
• Coolant temperature sensor
• Transmission fault

• P1372 — OBD2 code P1372 flags a problem with the ignition system (ignition spare). Short, gentle driving to a shop is usually possible. Common culprits: damaged coil wiring or connector, faulty ignition control circuit in the ECM, worn spark plugs or wrong plug gap.
• P1374 — P1374 — Engine Temperature Light Monitor Failure. A fault in the engine cooling and temperature control. Short, gentle driving to a shop is usually possible. Typical causes: low coolant level or air in the system, failed cooling fan or fan relay, water pump or radiator issues.
• P1375 — P1375 — Insufficient RMP Increase During Spark Test. 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, control module driver fault, corroded, loose or damaged connector.
• P1377 — P1377 — Injector Shutoff From Excessive Voltage. P1377 can indicate that injector operation has been disabled, increasing the risk of stalling or failure to start.
• P1378 — P1378 — FICM Low Supply Voltage. If the engine stalls, runs poorly, or will not start, avoid further driving because continued operation with inadequate FICM voltage may damage injector-control circuitry.
• P1379 — P1379 — Fuel Injection Control Module Overvoltage. P1379 indicates excessive voltage reaching the fuel injection control module, which can damage electronic modules.
• P1380 — P1380 — Ignition Coil - Cylinder 2 - Early Activation Fault. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: moisture or oil in the spark plug wells, damaged coil wiring or connector, failed ignition coil or coil pack.
• P1381 — P1381 — Ignition Coil - Cylinder 3 - Early Activation Fault. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: moisture or oil in the spark plug wells, faulty ignition control circuit in the ECM, worn spark plugs or wrong plug gap.
• P1382 — OBD2 code P1382 flags a problem with the crankshaft position sensing (crankshaft position (ckp)/ignition coil - cylinder 4 - early activation fault). Driving is not recommended until fixed. Common culprits: incorrect sensor air gap, ECM signal processing fault, damaged sensor wiring or connector.
• P1384 — OBD2 code P1384 flags a problem with the ignition system (ignition coil - cylinder 6 - early activation fault). Short, gentle driving to a shop is usually possible. Common culprits: worn spark plugs or wrong plug gap, failed ignition coil or coil pack, faulty ignition control circuit in the ECM.
• P1385 — P1385 — Misfire Detected - Rough Road Data Not Available. A fault in the engine misfire monitoring. Short, gentle driving to a shop is usually possible. Typical causes: vacuum leak in the intake, clogged or leaking fuel injector, incorrect fuel pressure or a weak fuel pump.
• P1386 — P1386 — Variable Cam Timing Overadvanced (Bank #1)/ Misfire Detected - No Communication with BCM. A fault in the engine misfire monitoring. Short, gentle driving to a shop is usually possible. Typical causes: incorrect fuel pressure or a weak fuel pump, worn or fouled spark plugs, failed ignition coil or coil wiring.
• P1387 — OBD2 code P1387 flags a problem with the sensor and actuator circuits (variable cam timing solenoid #1 circuit malfunction). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit.
• P1388 — Variable Cam Timing Overretarded (Bank #1) (P1388): a powertrain (engine/transmission) fault affecting the camshaft position and variable valve timing. Short, gentle driving to a shop is usually possible. Most often caused by worn timing chain/belt or jumped timing, worn cam phaser, faulty camshaft position sensor.
• P1390 — OBD2 code P1390 flags a problem with the sensor and actuator circuits (variable cam timing solenoid b malfunction). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit, corroded, loose or damaged connector.
• P1391 — OBD2 code P1391 flags a problem with the camshaft position and variable valve timing (variable cam timing overadvanced (bank #2)). Short, gentle driving to a shop is usually possible. Common culprits: faulty camshaft position sensor, damaged sensor wiring or reluctor ring, worn cam phaser.
• P1392 — Variable Cam Timing Solenoid #2 Circuit Malfunction (P1392): 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, corroded, loose or damaged connector, control module driver fault.
• P1393 — Variable Cam Timing Overretarded (Bank #2) (P1393): a powertrain (engine/transmission) fault affecting the camshaft position and variable valve timing. Short, gentle driving to a shop is usually possible. Most often caused by stuck or clogged VVT oil control valve (OCV), worn timing chain/belt or jumped timing, damaged sensor wiring or reluctor ring.
• P1394 — OBD2 code P1394 flags a problem with the diesel glow plug system (glow plug circuit high side low input). The car is usually drivable while you plan the repair. Common culprits: blown fuse in the glow plug circuit, damaged glow plug wiring or connector, burned-out glow plug.
• P1395 — P1395 — Octane Adjust Pin Out Of Self Test Range. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: faulty sensor or actuator of the affected circuit, poor ground connection, open or shorted wiring in the circuit.
• P1396 — Glow Plug Circuit Low Input (Bank #1) (P1396): a powertrain (engine/transmission) fault affecting the diesel glow plug system. The car is usually drivable while you plan the repair. Most often caused by blown fuse in the glow plug circuit, corroded glow plug connectors, damaged glow plug wiring or connector.
• P1398 — P1398 — Glow Plug Circuit Low Input (Bank #2). A fault in the diesel glow plug system. The car is usually drivable while you plan the repair. Typical causes: damaged glow plug wiring or connector, blown fuse in the glow plug circuit, corroded glow plug connectors.
• P1399 — Glow Plug Circuit High Input (Bank #2) (P1399): a powertrain (engine/transmission) fault affecting the diesel glow plug system. The car is usually drivable while you plan the repair. Most often caused by faulty glow plug relay or control module, damaged glow plug wiring or connector, burned-out glow plug.
• P1400 — Glow Plug Monitor Fault (Bank #1) (P1400): a powertrain (engine/transmission) fault affecting the diesel glow plug system. The car is usually drivable while you plan the repair. Most often caused by faulty glow plug relay or control module, damaged glow plug wiring or connector, blown fuse in the glow plug circuit.