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

• P1401 — Glow Plug Monitor Fault (Bank #2) (P1401): a powertrain (engine/transmission) fault affecting the diesel glow plug system. The car is usually drivable while you plan the repair. Most often caused by burned-out glow plug, corroded glow plug connectors, damaged glow plug wiring or connector.
• P1402 — System Voltage Out Of Self Test Range (P1402): 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, blown fuse feeding the circuit, corroded, loose or damaged connector.
• P1404 — P1404 — Glow Plug Circuit High Side. A fault in the diesel glow plug system. The car is usually drivable while you plan the repair. Typical causes: corroded glow plug connectors, damaged glow plug wiring or connector, faulty glow plug relay or control module.
• P1405 — P1405 — DPFE Circuit Low Input. 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.
• P1406 — P1406 — DPFE Circuit High Input. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: control module driver fault, open or shorted wiring in the circuit, poor ground connection.
• P1408 — P1408 — DPFE Sensor Hoses Reversed. 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, open or shorted wiring in the circuit.
• P1411 — P1411 — DPFE Sensor Upstream Hose Off Or Plugged. 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, poor ground connection.
• P1412 — P1412 — Frozen Exhaust Gas Recirculation Valve. P1412 is usually not an immediate no-drive fault, but a frozen EGR valve can cause rough idle, hesitation, poor emissions performance, and excessive exhaust temperature.
• P1414 — OBD2 code P1414 flags a problem with the exhaust gas recirculation (EGR) system (EGR no flow detected). The car is usually drivable while you plan the repair. Common culprits: ECM control circuit fault, vacuum leaks in EGR control lines, failed EGR valve or position sensor.
• P1416 — EVR Control Circuit Malfunction (P1416): 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.
• P1417 — P1417 — SAI System Incorrect Downstream Flow Detected. 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, corroded, loose or damaged connector.
• P1418 — P1418 — SAI System Monitor Circuit Low Input. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: corroded, loose or damaged connector, control module driver fault, faulty sensor or actuator of the affected circuit.
• P1419 — OBD2 code P1419 flags a problem with the sensor and actuator circuits (SAI system monitor circuit high input). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, poor ground connection, open or shorted wiring in the circuit.
• P1420 — P1420 — Air Pump Circuit Malfunction/ (AIR) System 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, control module driver fault, faulty sensor or actuator of the affected circuit.
• P1421 — P1421 — Port Air Circuit Malfunction/ (AIR) System 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, poor ground connection, control module driver fault.
• P1422 — OBD2 code P1422 flags a problem with the sensor and actuator circuits (port air relief circuit malfunction). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, faulty sensor or actuator of the affected circuit, open or shorted wiring in the circuit.
• P1423 — Split Air #1 Circuit Malfunction (P1423): 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, corroded, loose or damaged connector.
• P1424 — Split Air #2 Circuit Malfunction (P1424): 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.
• P1425 — OBD2 code P1425 flags a problem with the catalytic converter efficiency monitoring (catalyst temperature sensor failure). The car is usually drivable while you plan the repair. Common culprits: oil or coolant entering the exhaust, persistent rich or lean fuel mixture, engine misfires damaging the catalyst.
• P1426 — Catalyst Damage (P1426): a powertrain (engine/transmission) fault affecting the catalytic converter efficiency monitoring. The car is usually drivable while you plan the repair. Most often caused by oil or coolant entering the exhaust, faulty downstream or upstream oxygen sensor, exhaust leak ahead of the converter.
• P1427 — OBD2 code P1427 flags a problem with the sensor and actuator circuits (EGI temperature sensor failure). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, open or shorted wiring in the circuit, faulty sensor or actuator of the affected circuit.
• P1428 — OBD2 code P1428 flags a problem with the sensor and actuator circuits (EGI functionality test failed). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, poor ground connection, faulty sensor or actuator of the affected circuit.
• P1429 — P1429 — EGI Glow Plug Primary Failure. A fault in the diesel glow plug system. The car is usually drivable while you plan the repair. Typical causes: faulty glow plug relay or control module, corroded glow plug connectors, blown fuse in the glow plug circuit.
• P1430 — P1430 — EGI Glow Plug Secondary Failure. A fault in the diesel glow plug system. The car is usually drivable while you plan the repair. Typical causes: corroded glow plug connectors, burned-out glow plug, blown fuse in the glow plug circuit.