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

• P2676 — OBD2 code P2676 flags a problem with the sensor and actuator circuits (air cleaner inlet control 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, control module driver fault.
• P2677 — OBD2 code P2677 flags a problem with the sensor and actuator circuits (air cleaner inlet control circuit high). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, blown fuse feeding the circuit, corroded, loose or damaged connector.
• P2678 — OBD2 code P2678 flags a problem with the engine cooling and temperature control (coolant degassing valve control circuit/open). Short, gentle driving to a shop is usually possible. Common culprits: water pump or radiator issues, wiring faults in the sensor circuit, low coolant level or air in the system.
• P2679 — OBD2 code P2679 flags a problem with the engine cooling and temperature control (coolant degassing valve control circuit low). Short, gentle driving to a shop is usually possible. Common culprits: thermostat stuck open or closed, water pump or radiator issues, low coolant level or air in the system.
• P267A — B Rocker Arm Actuator Position Sensor Circuit Bank 2 (P267A): 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, poor ground connection, faulty sensor or actuator of the affected circuit.
• P267B — B Rocker Arm Actuator Position Sensor Circuit Range/Performance Bank 2 (P267B): 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, blown fuse feeding the circuit, corroded, loose or damaged connector.
• P267C — B Rocker Arm Actuator Position Sensor Circuit Low Bank 2 (P267C): 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, control module driver fault, open or shorted wiring in the circuit.
• P267D — P267D — B Rocker Arm Actuator Position Sensor Circuit High Bank 2. 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, corroded, loose or damaged connector, control module driver fault.
• P267E — P267E — B Rocker Arm Actuator Position Sensor Circuit Intermittent/Erratic Bank 2. 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.
• P267F — P267F — P2680 Coolant Degassing Valve Control Circuit High. A fault in the engine cooling and temperature control. Short, gentle driving to a shop is usually possible. Typical causes: thermostat stuck open or closed, failed cooling fan or fan relay, water pump or radiator issues.
• P2680 — P2680 — Coolant Degassing Valve Signal Too High. P2680 warrants prompt diagnosis because a degassing-valve or wiring fault can leave air in the cooling system.
• P2681 — P2681 — Engine Coolant Bypass Valve Control Circuit/Open. A fault in the engine cooling and temperature control. Short, gentle driving to a shop is usually possible. Typical causes: water pump or radiator issues, failed cooling fan or fan relay, wiring faults in the sensor circuit.
• P2682 — Engine Coolant Bypass Valve Control Circuit Low (P2682): a powertrain (engine/transmission) fault affecting the engine cooling and temperature control. Short, gentle driving to a shop is usually possible. Most often caused by wiring faults in the sensor circuit, faulty coolant temperature sensor, failed cooling fan or fan relay.
• P2683 — OBD2 code P2683 flags a problem with the engine cooling and temperature control (engine coolant bypass valve control circuit high). Short, gentle driving to a shop is usually possible. Common culprits: thermostat stuck open or closed, water pump or radiator issues, wiring faults in the sensor circuit.
• P2684 — P2684 — Actuator Supply Voltage "C" Circuit/Open. 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, blown fuse feeding the circuit, control module driver fault.
• P2685 — Actuator Supply Voltage "C" Circuit Low (P2685): 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, blown fuse feeding the circuit, control module driver fault.
• P2686 — P2686 — Actuator Supply Voltage "C" 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, control module driver fault, blown fuse feeding the circuit.
• P268B — OBD2 code P268B flags a problem with the fuel delivery and mixture control (high pressure fuel pump calibration not learned/programmed). Short, gentle driving to a shop is usually possible. Common culprits: clogged or leaking fuel injectors, vacuum or intake leaks skewing the mixture, contaminated or incorrect fuel.
• P268C — OBD2 code P268C flags a problem with the fuel delivery and mixture control (cylinder 1 injector data incompatible). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel rail pressure sensor or wiring, weak fuel pump or clogged fuel filter, clogged or leaking fuel injectors.
• P268D — Cylinder 2 Injector Data Incompatible (P268D): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by clogged or leaking fuel injectors, faulty fuel pressure regulator, faulty fuel rail pressure sensor or wiring.
• P268E — Cylinder 3 Injector Data Incompatible (P268E): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by clogged or leaking fuel injectors, contaminated or incorrect fuel, vacuum or intake leaks skewing the mixture.
• P268F — OBD2 code P268F flags a problem with the fuel delivery and mixture control (cylinder 4 injector data incompatible). Short, gentle driving to a shop is usually possible. Common culprits: clogged or leaking fuel injectors, faulty fuel rail pressure sensor or wiring, faulty fuel pressure regulator.
• P2690 — Cylinder 5 Injector Data Incompatible (P2690): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by vacuum or intake leaks skewing the mixture, faulty fuel pressure regulator, faulty fuel rail pressure sensor or wiring.
• P2691 — P2691 — Cylinder 6 Injector Data Incompatible. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: vacuum or intake leaks skewing the mixture, weak fuel pump or clogged fuel filter, clogged or leaking fuel injectors.