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

• C1249 — OBD2 code C1249 flags a problem with the ignition system (ABS outlet valve coil RR circuit short to ground). Short, gentle driving to a shop is usually possible. Common culprits: damaged coil wiring or connector, failed ignition coil or coil pack, moisture or oil in the spark plug wells.
• C1250 — C1250 — ABS Inlet Valve Coil LR Circuit Failure. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: damaged coil wiring or connector, moisture or oil in the spark plug wells, faulty ignition control circuit in the ECM.
• C1251 — C1251 — ABS Inlet Valve Coil LR Circuit Open. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: faulty ignition control circuit in the ECM, failed ignition coil or coil pack, worn spark plugs or wrong plug gap.
• C1252 — C1252 — ABS Inlet Valve Coil LR Circuit Short To Battery. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: moisture or oil in the spark plug wells, worn spark plugs or wrong plug gap, faulty ignition control circuit in the ECM.
• C1253 — C1253 — ABS Inlet Valve Coil LR Circuit Short To Ground. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: failed ignition coil or coil pack, moisture or oil in the spark plug wells, worn spark plugs or wrong plug gap.
• C1254 — OBD2 code C1254 flags a problem with the ignition system (ABS inlet valve coil RR circuit failure). Short, gentle driving to a shop is usually possible. Common culprits: failed ignition coil or coil pack, damaged coil wiring or connector, worn spark plugs or wrong plug gap.
• C1255 — ABS Inlet Valve Coil RR Circuit Open (C1255): a chassis (brakes/steering/suspension) fault affecting the ignition system. Short, gentle driving to a shop is usually possible. Most often caused by damaged coil wiring or connector, worn spark plugs or wrong plug gap, faulty ignition control circuit in the ECM.
• C1256 — OBD2 code C1256 flags a problem with the ignition system (ABS inlet valve coil RR circuit short to battery). Short, gentle driving to a shop is usually possible. Common culprits: damaged coil wiring or connector, worn spark plugs or wrong plug gap, failed ignition coil or coil pack.
• C1257 — C1257 — ABS Inlet Valve Coil RR Circuit Short To Ground. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: moisture or oil in the spark plug wells, worn spark plugs or wrong plug gap, faulty ignition control circuit in the ECM.
• C1258 — OBD2 code C1258 flags a problem with the sensor and actuator circuits (speed wheel LF comparison failure). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, blown fuse feeding the circuit, open or shorted wiring in the circuit.
• C1259 — C1259 — Speed Wheel RF Comparison Failure. 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, blown fuse feeding the circuit.
• C1260 — Speed Wheel RR Comparison Failure (C1260): a chassis (brakes/steering/suspension) 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.
• C1261 — OBD2 code C1261 flags a problem with the sensor and actuator circuits (speed wheel LR comparison failure). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, poor ground connection, blown fuse feeding the circuit.
• C1262 — OBD2 code C1262 flags a problem with the sensor and actuator circuits (lamp warning relay circuit failure). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, poor ground connection, faulty sensor or actuator of the affected circuit.
• C1263 — C1263 — Lamp Warning Relay Circuit Open. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: control module driver fault, corroded, loose or damaged connector, poor ground connection.
• C1264 — Lamp Warning Relay Circuit Short To Battery (C1264): a chassis (brakes/steering/suspension) 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.
• C1265 — Lamp Warning Relay Circuit Short To Ground (C1265): a chassis (brakes/steering/suspension) 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.
• C1266 — C1266 — ABS Valve Power Relay Circuit Failure. A fault in the ABS / stability control. Short, gentle driving to a shop is usually possible. Typical causes: failed wheel speed sensor, faulty ABS module or pump motor, blown fuse or low voltage to the ABS module.
• C1267 — ABS Functions Temporarily Disabled (C1267): a chassis (brakes/steering/suspension) fault affecting the ABS / stability control. Short, gentle driving to a shop is usually possible. Most often caused by damaged tone (reluctor) ring on the hub, failed wheel speed sensor, blown fuse or low voltage to the ABS module.
• C1268 — OBD2 code C1268 flags a problem with the sensor and actuator circuits (motor relay # 1 circuit failure). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, poor ground connection, corroded, loose or damaged connector.
• C1269 — Motor Relay # 1 Circuit Short to Battery (C1269): a chassis (brakes/steering/suspension) 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.
• C1270 — C1270 — Motor # 1 Input Circuit Failure. 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, faulty sensor or actuator of the affected circuit.
• C1271 — C1271 — Motor # 1 Input Circuit Short to Gnd. 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, blown fuse feeding the circuit, open or shorted wiring in the circuit.
• C1272 — C1272 — Motor # 2 Input Circuit Failure. 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, poor ground connection.