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

• P2630 — P2630 — O2 Sensor Pumping Current Trim Circuit Low Bank 2 Sensor 1. A fault in the oxygen sensor circuit. The car is usually drivable while you plan the repair. Typical causes: aged or contaminated oxygen sensor, oil or coolant contamination of the sensor tip, damaged sensor wiring or connector.
• P2631 — OBD2 code P2631 flags a problem with the oxygen sensor circuit (O2 sensor pumping current trim circuit high bank 2 sensor 1). The car is usually drivable while you plan the repair. Common culprits: ECM signal circuit fault, blown sensor heater fuse, exhaust leak near the sensor.
• P2632 — OBD2 code P2632 flags a problem with the fuel delivery and mixture control (fuel pump "B" control circuit /open). Short, gentle driving to a shop is usually possible. Common culprits: vacuum or intake leaks skewing the mixture, contaminated or incorrect fuel, weak fuel pump or clogged fuel filter.
• P2633 — OBD2 code P2633 flags a problem with the fuel delivery and mixture control (fuel pump "B" control circuit low). Short, gentle driving to a shop is usually possible. Common culprits: contaminated or incorrect fuel, faulty fuel pressure regulator, vacuum or intake leaks skewing the mixture.
• P2634 — Fuel Pump "B" Control Circuit High (P2634): 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 contaminated or incorrect fuel, vacuum or intake leaks skewing the mixture, faulty fuel pressure regulator.
• P2635 — OBD2 code P2635 flags a problem with the fuel delivery and mixture control (fuel pump "A" low flow/performance). Short, gentle driving to a shop is usually possible. Common culprits: vacuum or intake leaks skewing the mixture, clogged or leaking fuel injectors, contaminated or incorrect fuel.
• P2636 — P2636 — Fuel Pump "B" Low Flow/Performance. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: weak fuel pump or clogged fuel filter, vacuum or intake leaks skewing the mixture, faulty fuel rail pressure sensor or wiring.
• P2637 — P2637 — Torque Management Feedback Signal "A". A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: blown fuse feeding the circuit, control module driver fault, poor ground connection.
• P2638 — OBD2 code P2638 flags a problem with the sensor and actuator circuits (torque management feedback signal "A" range/performance). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, blown fuse feeding the circuit, control module driver fault.
• P2640 — P2640 — Torque Management Feedback Signal "A" 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.
• P2641 — Torque Management Feedback Signal "B" (P2641): 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, poor ground connection.
• P2642 — P2642 — Torque Management Feedback Signal "B" 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, faulty sensor or actuator of the affected circuit, control module driver fault.
• P2643 — Torque Management Feedback Signal "B" Low (P2643): 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, blown fuse feeding the circuit, corroded, loose or damaged connector.
• P2644 — Torque Management Feedback Signal "B" High (P2644): 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.
• P2646 — A Rocker Arm Actuator System Performance/Stuck Off Bank 1 (P2646): 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, control module driver fault, poor ground connection.
• P2648 — A Rocker Arm Actuator Control Circuit Low Bank 1 (P2648): 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, poor ground connection.
• P2649 — P2649 — A Rocker Arm Actuator Control Circuit High Bank 1. 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, corroded, loose or damaged connector.
• P264A — OBD2 code P264A flags a problem with the sensor and actuator circuits (a rocker arm actuator position sensor circuit bank 1). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, faulty sensor or actuator of the affected circuit, control module driver fault.
• P264B — P264B — A Rocker Arm Actuator Position Sensor Circuit Range/Performance Bank 1. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit, corroded, loose or damaged connector.
• P264C — A Rocker Arm Actuator Position Sensor Circuit Low Bank 1 (P264C): 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, faulty sensor or actuator of the affected circuit.
• P264D — A Rocker Arm Actuator Position Sensor Circuit High Bank 1 (P264D): 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, blown fuse feeding the circuit.
• P264E — P264E — A Rocker Arm Actuator Position Sensor Circuit Intermittent/Erratic Bank 1. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: blown fuse feeding the circuit, corroded, loose or damaged connector, open or shorted wiring in the circuit.
• P2650 — P2650 — B Rocker Arm Actuator Control Circuit/Open Bank 1. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: blown fuse feeding the circuit, control module driver fault, corroded, loose or damaged connector.
• P2652 — P2652 — B Rocker Arm Actuator System Stuck On Bank 1. 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, blown fuse feeding the circuit.