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

• P2422 — Evaporative Emission System Vent Valve Stuck Closed (P2422): a powertrain (engine/transmission) fault affecting the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Most often caused by cracked EVAP hoses or lines, small leak in the fuel tank or filler neck, faulty purge valve (canister purge solenoid).
• P2424 — OBD2 code P2424 flags a problem with the catalytic converter efficiency monitoring (HC adsorption catalyst efficiency below threshold bank 2). The car is usually drivable while you plan the repair. Common culprits: faulty downstream or upstream oxygen sensor, engine misfires damaging the catalyst, exhaust leak ahead of the converter.
• P2425 — P2425 — Exhaust Gas Recirculation Cooling Valve Control Circuit/Open. A fault in the exhaust gas recirculation (EGR) system. The car is usually drivable while you plan the repair. Typical causes: ECM control circuit fault, carbon buildup blocking the EGR valve or passages, failed EGR valve or position sensor.
• P2426 — OBD2 code P2426 flags a problem with the exhaust gas recirculation (EGR) system (exhaust gas recirculation cooling valve control circuit low). The car is usually drivable while you plan the repair. Common culprits: failed EGR valve or position sensor, vacuum leaks in EGR control lines, carbon buildup blocking the EGR valve or passages.
• P2427 — P2427 — Exhaust Gas Recirculation Cooling Valve Control Circuit High. A fault in the exhaust gas recirculation (EGR) system. The car is usually drivable while you plan the repair. Typical causes: faulty EGR solenoid or wiring, vacuum leaks in EGR control lines, ECM control circuit fault.
• P2428 — Exhaust Gas Temperature Too High Bank 1 (P2428): 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, faulty sensor or actuator of the affected circuit, control module driver fault.
• P2429 — P2429 — Exhaust Gas Temperature Too 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, blown fuse feeding the circuit, control module driver fault.
• P242A — Exhaust Gas Temperature Sensor Circuit Bank 1 Sensor 3 (P242A): 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, poor ground connection, blown fuse feeding the circuit.
• P242B — Exhaust Gas Temperature Sensor Circuit Range/Performance Bank 1 Sensor 3 (P242B): 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.
• P242C — OBD2 code P242C flags a problem with the sensor and actuator circuits (exhaust gas temperature sensor circuit low bank 1 sensor 3). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit.
• P242D — P242D — Exhaust Gas Temperature Sensor Circuit High Bank 1 Sensor 3. 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, control module driver fault.
• P242E — Exhaust Gas Temperature Sensor Circuit Intermittent/Erratic Bank 1 Sensor 3 (P242E): 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, poor ground connection, blown fuse feeding the circuit.
• P2430 — OBD2 code P2430 flags a problem with the sensor and actuator circuits (secondary air injection system air flow/pressure sensor circuit bank 1). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, corroded, loose or damaged connector, blown fuse feeding the circuit.
• P2431 — OBD2 code P2431 flags a problem with the sensor and actuator circuits (secondary air injection system air flow/pressure sensor circuit range/performance bank 1). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, corroded, loose or damaged connector, blown fuse feeding the circuit.
• P2432 — P2432 — Secondary Air Injection System Air Flow/Pressure Sensor Circuit Low 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, faulty sensor or actuator of the affected circuit.
• P2435 — OBD2 code P2435 flags a problem with the sensor and actuator circuits (secondary air injection system air flow/pressure sensor circuit bank 2). 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.
• P2436 — Secondary Air Injection System Air Flow/Pressure Sensor Circuit Range/Performance Bank 2 (P2436): 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.
• P2437 — OBD2 code P2437 flags a problem with the sensor and actuator circuits (secondary air injection system air flow/pressure sensor circuit low bank 2). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, corroded, loose or damaged connector, blown fuse feeding the circuit.
• P2438 — OBD2 code P2438 flags a problem with the sensor and actuator circuits (secondary air injection system air flow/pressure sensor circuit high bank 2). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, corroded, loose or damaged connector, blown fuse feeding the circuit.
• P2439 — P2439 — Secondary Air Injection System Air Flow/Pressure 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: blown fuse feeding the circuit, open or shorted wiring in the circuit, faulty sensor or actuator of the affected circuit.
• P2440 — Secondary Air Injection System Switching Valve Stuck Open Bank 1 (P2440): 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.
• P2442 — OBD2 code P2442 flags a problem with the sensor and actuator circuits (secondary air injection system switching valve stuck open bank 2). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, corroded, loose or damaged connector, poor ground connection.
• P2443 — OBD2 code P2443 flags a problem with the sensor and actuator circuits (secondary air injection system switching valve stuck closed bank 2). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, control module driver fault, poor ground connection.
• P2444 — Secondary Air Injection System Pump Stuck On Bank 1 (P2444): 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.