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

• P2036 — OBD2 code P2036 flags a problem with the sensor and actuator circuits (exhaust gas temperature sensor circuit high bank 2 sensor 2). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, open or shorted wiring in the circuit, faulty sensor or actuator of the affected circuit.
• P2037 — OBD2 code P2037 flags a problem with the sensor and actuator circuits (reductant injection air pressure sensor "A" circuit). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, open or shorted wiring in the circuit, corroded, loose or damaged connector.
• P2038 — Reductant Injection Air Pressure Sensor "A" Circuit Range/Performance (P2038): 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, open or shorted wiring in the circuit.
• P2039 — OBD2 code P2039 flags a problem with the sensor and actuator circuits (reductant injection air pressure sensor "A" circuit low). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit.
• P203A — P203A — Reductant Level Sensor Circuit. 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, poor ground connection.
• P203B — P203B — Reductant Level Sensor Circuit Range/Performance. 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.
• P203C — OBD2 code P203C flags a problem with the sensor and actuator circuits (reductant level sensor circuit low). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, control module driver fault, poor ground connection.
• P203D — Reductant Level Sensor Circuit High (P203D): 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, faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit.
• P203E — OBD2 code P203E flags a problem with the sensor and actuator circuits (reductant level sensor circuit intermittent/erratic). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, blown fuse feeding the circuit, open or shorted wiring in the circuit.
• P2040 — P2040 — Reductant Injection Air Pressure Sensor "A" 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.
• P2041 — Reductant Injection Air Pressure Sensor "A" Circuit Intermittent (P2041): 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, blown fuse feeding the circuit.
• P2043 — P2043 — Reductant Temperature Sensor Circuit 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, control module driver fault, blown fuse feeding the circuit.
• P2044 — Reductant Temperature Sensor Circuit Low (P2044): 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, poor ground connection.
• P2046 — P2046 — Reductant Temperature Sensor Circuit Intermittent. 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.
• P2048 — OBD2 code P2048 flags a problem with the sensor and actuator circuits (reductant injection valve circuit low bank 1 unit 1). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit, control module driver fault.
• P2049 — OBD2 code P2049 flags a problem with the sensor and actuator circuits (reductant injection valve circuit high bank 1 unit 1). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, control module driver fault, open or shorted wiring in the circuit.
• P204B — OBD2 code P204B flags a problem with the sensor and actuator circuits (reductant pressure sensor circuit range/performance). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, control module driver fault, poor ground connection.
• P204C — OBD2 code P204C flags a problem with the sensor and actuator circuits (reductant pressure sensor circuit low). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, open or shorted wiring in the circuit, corroded, loose or damaged connector.
• P204D — P204D — Reductant Pressure Sensor Circuit High. 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, poor ground connection.
• P204E — OBD2 code P204E flags a problem with the sensor and actuator circuits (reductant pressure sensor circuit intermittent/erratic). 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.
• P204F — OBD2 code P204F flags a problem with the sensor and actuator circuits (reductant system performance bank 1). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, open or shorted wiring in the circuit, poor ground connection.
• P2050 — Reductant Injection Valve Circuit/Open Bank 2 Unit 1 (P2050): 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, corroded, loose or damaged connector, open or shorted wiring in the circuit.
• P2051 — Reductant Injection Valve Circuit Low Bank 2 Unit 1 (P2051): 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, open or shorted wiring in the circuit.
• P2052 — Reductant Injection Valve Circuit High Bank 2 Unit 1 (P2052): 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.