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

• P047E — OBD2 code P047E flags a problem with the sensor and actuator circuits (exhaust pressure sensor "B" circuit intermittent/erratic). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit.
• P047F — Exhaust Pressure Control Valve "A" Stuck Open (P047F): 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, open or shorted wiring in the circuit.
• P0480 — Cooling Fan I Control Circuit Malfunction (P0480): 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, water pump or radiator issues.
• P0481 — Cooling Fan 2 Control Circuit Malfunction (P0481): 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 faulty coolant temperature sensor, thermostat stuck open or closed, wiring faults in the sensor circuit.
• P0482 — OBD2 code P0482 flags a problem with the engine cooling and temperature control (cooling fan 3 control circuit malfunction). Short, gentle driving to a shop is usually possible. Common culprits: faulty coolant temperature sensor, failed cooling fan or fan relay, thermostat stuck open or closed.
• P0483 — P0483 — Cooling Fan Rationality Check Malfunction. 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, low coolant level or air in the system, thermostat stuck open or closed.
• P0484 — P0484 — Cooling Fan Circuit Over Current. A fault in the engine cooling and temperature control. Short, gentle driving to a shop is usually possible. Typical causes: faulty coolant temperature sensor, low coolant level or air in the system, water pump or radiator issues.
• P0485 — Cooling Fan Power/Ground Circuit Malfunction (P0485): 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 low coolant level or air in the system, thermostat stuck open or closed, wiring faults in the sensor circuit.
• P0486 — OBD2 code P0486 flags a problem with the exhaust gas recirculation (EGR) system (exhaust gas recirculation sensor "B" circuit). The car is usually drivable while you plan the repair. Common culprits: failed EGR valve or position sensor, vacuum leaks in EGR control lines, faulty EGR solenoid or wiring.
• P0487 — Exhaust Gas Recirculation Throttle Control Circuit "A" Open (P0487): a powertrain (engine/transmission) fault affecting the exhaust gas recirculation (EGR) system. The car is usually drivable while you plan the repair. Most often caused by ECM control circuit fault, vacuum leaks in EGR control lines, failed EGR valve or position sensor.
• P0488 — OBD2 code P0488 flags a problem with the exhaust gas recirculation (EGR) system (exhaust gas recirculation throttle control circuit "A" range/performance). The car is usually drivable while you plan the repair. Common culprits: failed EGR valve or position sensor, faulty EGR solenoid or wiring, vacuum leaks in EGR control lines.
• P0489 — Exhaust Gas Recirculation "A" Control Circuit Low (P0489): a powertrain (engine/transmission) fault affecting the exhaust gas recirculation (EGR) system. The car is usually drivable while you plan the repair. Most often caused by carbon buildup blocking the EGR valve or passages, vacuum leaks in EGR control lines, failed EGR valve or position sensor.
• P048A — Exhaust Pressure Control Valve "A" Stuck Closed (P048A): 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, open or shorted wiring in the circuit, corroded, loose or damaged connector.
• P048B — Exhaust Pressure Control Valve Position Sensor/Switch Circuit (P048B): 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, blown fuse feeding the circuit.
• P048C — Exhaust Pressure Control Valve Position Sensor/Switch Circuit Range/Performance (P048C): 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 poor ground connection, faulty sensor or actuator of the affected circuit, corroded, loose or damaged connector.
• P048D — Exhaust Pressure Control Valve Position Sensor/Switch Circuit Low (P048D): 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, blown fuse feeding the circuit.
• P048E — P048E — Exhaust Pressure Control Valve Position Sensor/Switch 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, corroded, loose or damaged connector, blown fuse feeding the circuit.
• P048F — OBD2 code P048F flags a problem with the sensor and actuator circuits (exhaust pressure control valve position sensor/switch circuit intermittent/erratic). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, poor ground connection, blown fuse feeding the circuit.
• P0490 — Exhaust Gas Recirculation "A" Control Circuit High (P0490): a powertrain (engine/transmission) fault affecting the exhaust gas recirculation (EGR) system. The car is usually drivable while you plan the repair. Most often caused by vacuum leaks in EGR control lines, faulty EGR solenoid or wiring, carbon buildup blocking the EGR valve or passages.
• P0491 — Secondary Air Injection System Insufficient Flow Bank 1 (P0491): 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 open or shorted wiring in the circuit, corroded, loose or damaged connector, blown fuse feeding the circuit.
• P0492 — Secondary Air Injection System Insufficient Flow Bank 2 (P0492): 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, faulty sensor or actuator of the affected circuit.
• P0493 — P0493 — Fan Overspeed. 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, blown fuse feeding the circuit.
• P0494 — OBD2 code P0494 flags a problem with the sensor and actuator circuits (fan speed low). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, poor ground connection, corroded, loose or damaged connector.
• P0495 — Fan Speed High (P0495): 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 open or shorted wiring in the circuit, corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit.