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

• P0240 — P0240 — Turbocharger Boost Sensor B Circuit Range/Performance. A fault in the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Typical causes: clogged intake or exhaust (DPF/cat), stuck wastegate or faulty boost control solenoid, faulty boost pressure sensor.
• P0241 — Turbocharger Boost Sensor B Circuit Low (P0241): a powertrain (engine/transmission) fault affecting the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Most often caused by clogged intake or exhaust (DPF/cat), faulty boost pressure sensor, boost leak in intercooler piping or hoses.
• P0242 — P0242 — Turbocharger Boost Sensor B Circuit High. A fault in the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Typical causes: boost leak in intercooler piping or hoses, worn turbocharger, clogged intake or exhaust (DPF/cat).
• P0243 — OBD2 code P0243 flags a problem with the turbocharger / supercharger boost control (turbocharger wastegate solenoid a malfunction). Short, gentle driving to a shop is usually possible. Common culprits: boost leak in intercooler piping or hoses, faulty boost pressure sensor, clogged intake or exhaust (DPF/cat).
• P0244 — OBD2 code P0244 flags a problem with the turbocharger / supercharger boost control (turbocharger wastegate solenoid a range/performance). Short, gentle driving to a shop is usually possible. Common culprits: boost leak in intercooler piping or hoses, vacuum or actuator line damage, faulty boost pressure sensor.
• P0245 — OBD2 code P0245 flags a problem with the turbocharger / supercharger boost control (turbocharger wastegate solenoid a low). Short, gentle driving to a shop is usually possible. Common culprits: worn turbocharger, vacuum or actuator line damage, clogged intake or exhaust (DPF/cat).
• P0246 — Turbocharger Wastegate Solenoid A High (P0246): a powertrain (engine/transmission) fault affecting the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Most often caused by clogged intake or exhaust (DPF/cat), faulty boost pressure sensor, stuck wastegate or faulty boost control solenoid.
• P0247 — OBD2 code P0247 flags a problem with the turbocharger / supercharger boost control (turbocharger wastegate solenoid b malfunction). Short, gentle driving to a shop is usually possible. Common culprits: boost leak in intercooler piping or hoses, worn turbocharger, clogged intake or exhaust (DPF/cat).
• P0248 — OBD2 code P0248 flags a problem with the turbocharger / supercharger boost control (turbocharger wastegate solenoid b range/performance). Short, gentle driving to a shop is usually possible. Common culprits: stuck wastegate or faulty boost control solenoid, faulty boost pressure sensor, worn turbocharger.
• P0249 — Turbocharger Wastegate Solenoid B Low (P0249): a powertrain (engine/transmission) fault affecting the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Most often caused by stuck wastegate or faulty boost control solenoid, clogged intake or exhaust (DPF/cat), boost leak in intercooler piping or hoses.
• P024A — P024A — Charge Air Cooler Bypass Control "A" 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, corroded, loose or damaged connector, blown fuse feeding the circuit.
• P024B — Charge Air Cooler Bypass Control "A" Stuck (P024B): 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.
• P024C — Charge Air Cooler Bypass Position Sensor "A" Circuit (P024C): 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, faulty sensor or actuator of the affected circuit, open or shorted wiring in the circuit.
• P024D — OBD2 code P024D flags a problem with the sensor and actuator circuits (charge air cooler bypass position sensor "A" circuit range/performance). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, faulty sensor or actuator of the affected circuit, corroded, loose or damaged connector.
• P024E — OBD2 code P024E flags a problem with the sensor and actuator circuits (charge air cooler bypass position sensor "A" circuit low). 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.
• P024F — P024F — Charge Air Cooler Bypass Position Sensor "A" Circuit High. 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.
• P0250 — Turbocharger Wastegate Solenoid B High (P0250): a powertrain (engine/transmission) fault affecting the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Most often caused by worn turbocharger, stuck wastegate or faulty boost control solenoid, faulty boost pressure sensor.
• P0251 — OBD2 code P0251 flags a problem with the fuel delivery and mixture control (injection pump fuel metering control a malfunction (Cam/Rotor/Injector)). Short, gentle driving to a shop is usually possible. Common culprits: weak fuel pump or clogged fuel filter, vacuum or intake leaks skewing the mixture, faulty fuel rail pressure sensor or wiring.
• P0252 — P0252 — Injection Pump Fuel Metering Control A Range/Performance (Cam/Rotor/Injector). A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: weak fuel pump or clogged fuel filter, faulty fuel rail pressure sensor or wiring, faulty fuel pressure regulator.
• P0253 — Injection Pump Fuel Metering Control A Low (Cam/Rotor/Injector) (P0253): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by weak fuel pump or clogged fuel filter, contaminated or incorrect fuel, faulty fuel rail pressure sensor or wiring.
• P0254 — Injection Pump Fuel Metering Control A High (Cam/Rotor/Injector) (P0254): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by faulty fuel rail pressure sensor or wiring, clogged or leaking fuel injectors, weak fuel pump or clogged fuel filter.
• P0255 — OBD2 code P0255 flags a problem with the fuel delivery and mixture control (injection pump fuel metering control a intermittent (Cam/Rotor/Injector)). Short, gentle driving to a shop is usually possible. Common culprits: clogged or leaking fuel injectors, contaminated or incorrect fuel, faulty fuel rail pressure sensor or wiring.
• P0256 — P0256 — Injection Pump Fuel Metering Control B Malfunction (Cam/Rotor/Injector). A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: faulty fuel pressure regulator, contaminated or incorrect fuel, clogged or leaking fuel injectors.
• P0257 — Injection Pump Fuel Metering Control B Range/Performance Injector) (P0257): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by vacuum or intake leaks skewing the mixture, weak fuel pump or clogged fuel filter, clogged or leaking fuel injectors.