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

• P0679 — P0679 — Cylinder 9 Glow Plug Circuit. A fault in the diesel glow plug system. The car is usually drivable while you plan the repair. Typical causes: blown fuse in the glow plug circuit, damaged glow plug wiring or connector, corroded glow plug connectors.
• P067A — OBD2 code P067A flags a problem with the diesel glow plug system (cylinder 4 glow plug control circuit low). The car is usually drivable while you plan the repair. Common culprits: damaged glow plug wiring or connector, corroded glow plug connectors, burned-out glow plug.
• P067B — OBD2 code P067B flags a problem with the diesel glow plug system (cylinder 4 glow plug control circuit high). The car is usually drivable while you plan the repair. Common culprits: corroded glow plug connectors, faulty glow plug relay or control module, damaged glow plug wiring or connector.
• P067C — P067C — Cylinder 5 Glow Plug Control Circuit Low. A fault in the diesel glow plug system. The car is usually drivable while you plan the repair. Typical causes: blown fuse in the glow plug circuit, corroded glow plug connectors, damaged glow plug wiring or connector.
• P067D — Cylinder 5 Glow Plug Control Circuit High (P067D): 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, blown fuse in the glow plug circuit, damaged glow plug wiring or connector.
• P067E — OBD2 code P067E flags a problem with the diesel glow plug system (cylinder 6 glow plug control circuit low). The car is usually drivable while you plan the repair. Common culprits: faulty glow plug relay or control module, burned-out glow plug, corroded glow plug connectors.
• P067F — OBD2 code P067F flags a problem with the diesel glow plug system (cylinder 6 glow plug control circuit high). The car is usually drivable while you plan the repair. Common culprits: faulty glow plug relay or control module, corroded glow plug connectors, burned-out glow plug.
• P0680 — Cylinder 10 Glow Plug Circuit (P0680): 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, blown fuse in the glow plug circuit, damaged glow plug wiring or connector.
• P0681 — Cylinder 11 Glow Plug Circuit (P0681): 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, burned-out glow plug, blown fuse in the glow plug circuit.
• P0682 — OBD2 code P0682 flags a problem with the diesel glow plug system (cylinder 12 glow plug circuit). The car is usually drivable while you plan the repair. Common culprits: blown fuse in the glow plug circuit, faulty glow plug relay or control module, burned-out glow plug.
• P0683 — OBD2 code P0683 flags a problem with the diesel glow plug system (glow plug control module to PCM communication circuit). The car is usually drivable while you plan the repair. Common culprits: damaged glow plug wiring or connector, burned-out glow plug, blown fuse in the glow plug circuit.
• P0684 — P0684 — Glow Plug Control Module to PCM Communication Circuit Range/Performance. A fault in the diesel glow plug system. The car is usually drivable while you plan the repair. Typical causes: corroded glow plug connectors, damaged glow plug wiring or connector, blown fuse in the glow plug circuit.
• P0685 — OBD2 code P0685 flags a problem with the sensor and actuator circuits (ECM/PCM power relay control circuit open). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, control module driver fault, blown fuse feeding the circuit.
• P0686 — ECM/PCM Power Relay Control Circuit Low (P0686): 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, open or shorted wiring in the circuit, corroded, loose or damaged connector.
• P0687 — P0687 — ECM/PCM Power Relay Control Circuit High. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: control module driver fault, faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit.
• P0688 — P0688 — ECM/PCM Power Relay Sense Circuit Open. 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.
• P0689 — OBD2 code P0689 flags a problem with the sensor and actuator circuits (ECM/PCM power relay sense circuit low). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, poor ground connection, control module driver fault.
• P068A — OBD2 code P068A flags a problem with the sensor and actuator circuits (ECM/PCM power relay de-energized performance - too early). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, poor ground connection, blown fuse feeding the circuit.
• P068B — P068B — ECM/PCM Power Relay De-Energized Performance - Too Late. 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, open or shorted wiring in the circuit.
• P068C — OBD2 code P068C flags a problem with the diesel glow plug system (cylinder 7 glow plug control circuit low). The car is usually drivable while you plan the repair. Common culprits: damaged glow plug wiring or connector, blown fuse in the glow plug circuit, corroded glow plug connectors.
• P068D — Cylinder 7 Glow Plug Control Circuit High (P068D): 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 burned-out glow plug, damaged glow plug wiring or connector, corroded glow plug connectors.
• P068E — P068E — Cylinder 8 Glow Plug Control Circuit Low. A fault in the diesel glow plug system. The car is usually drivable while you plan the repair. Typical causes: burned-out glow plug, damaged glow plug wiring or connector, blown fuse in the glow plug circuit.
• P068F — OBD2 code P068F flags a problem with the diesel glow plug system (cylinder 8 glow plug control circuit high). The car is usually drivable while you plan the repair. Common culprits: damaged glow plug wiring or connector, burned-out glow plug, faulty glow plug relay or control module.
• P0690 — P0690 — ECM/PCM Power Relay Sense Circuit High. 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, open or shorted wiring in the circuit, control module driver fault.