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

• P1240 — OBD2 code P1240 flags a problem with the fuel delivery and mixture control (fuel pump control out of range). Short, gentle driving to a shop is usually possible. Common culprits: clogged or leaking fuel injectors, weak fuel pump or clogged fuel filter, vacuum or intake leaks skewing the mixture.
• P1241 — P1241 — Fuel Pump Control Out Of Range. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: faulty fuel rail pressure sensor or wiring, vacuum or intake leaks skewing the mixture, clogged or leaking fuel injectors.
• P1242 — OBD2 code P1242 flags a problem with the fuel delivery and mixture control (fuel pump secondary circuit malfunction). Short, gentle driving to a shop is usually possible. Common culprits: contaminated or incorrect fuel, weak fuel pump or clogged fuel filter, faulty fuel rail pressure sensor or wiring.
• P1243 — P1243 — Fuel Pump Secondary Circuit Malfunction. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: clogged or leaking fuel injectors, contaminated or incorrect fuel, faulty fuel rail pressure sensor or wiring.
• P1244 — P1244 — Speed Fuel Pump Positive Feed Fault. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: clogged or leaking fuel injectors, weak fuel pump or clogged fuel filter, contaminated or incorrect fuel.
• P1245 — Sensor Power Supply Malfunction (P1245): 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, open or shorted wiring in the circuit, blown fuse feeding the circuit.
• P1246 — OBD2 code P1246 flags a problem with the sensor and actuator circuits (sensor power supply low input). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, open or shorted wiring in the circuit, faulty sensor or actuator of the affected circuit.
• P1247 — P1247 — Sensor Power Supply 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, faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit.
• P1248 — OBD2 code P1248 flags a problem with the fuel delivery and mixture control (second fuel pump faulty or ground fault). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, weak fuel pump or clogged fuel filter, vacuum or intake leaks skewing the mixture.
• P1249 — OBD2 code P1249 flags a problem with the sensor and actuator circuits (alternator load input failed high). 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, blown fuse feeding the circuit.
• P1251 — Alternator Load Input Failed (P1251): 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.
• P1252 — P1252 — Turbo Boost Pressure Low. A fault in the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Typical causes: stuck wastegate or faulty boost control solenoid, worn turbocharger, clogged intake or exhaust (DPF/cat).
• P1253 — Turbo Boost Pressure Not Detected (P1253): a powertrain (engine/transmission) fault affecting the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Most often caused by boost leak in intercooler piping or hoses, faulty boost pressure sensor, vacuum or actuator line damage.
• P1254 — P1254 — Wastegate Control Valve Performance. A fault in the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Typical causes: worn turbocharger, clogged intake or exhaust (DPF/cat), vacuum or actuator line damage.
• P1255 — PRC Solenoid Circuit Malfunction (P1255): 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, blown fuse feeding the circuit, control module driver fault.
• P1256 — P1256 — Air Mixture Solenoid Circuit Malfunction. 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, corroded, loose or damaged connector, blown fuse feeding the circuit.
• P1257 — P1257 — Pedal Correlation PDS1 and LPDS High. 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, poor ground connection.
• P1258 — P1258 — Pedal Correlation PDS1 and LPDS Low. 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.
• P1259 — OBD2 code P1259 flags a problem with the sensor and actuator circuits (pedal correlation PDS2 and LPDS high). 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.
• P1260 — P1260: Do not drive if P1260 is currently active, the engine is being shut down by the immobilizer, or a theft concern remains unresolved.
• P1261 — OBD2 code P1261 flags a problem with the sensor and actuator circuits (pedal correlation PDS1 and HPDS). 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.
• P1262 — Pedal Correlation PDS2 and HPDS (P1262): 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, open or shorted wiring in the circuit.
• P1263 — OBD2 code P1263 flags a problem with the sensor and actuator circuits (pedal correlation PDS1 and PDS2). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, poor ground connection, corroded, loose or damaged connector.
• P1264 — Immobilizer to PCM Signal Error (P1264): 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, corroded, loose or damaged connector.