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

• P0258 — P0258 — Injection Pump Fuel Metering Control B Low (Cam/Rotor/Injector). A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: vacuum or intake leaks skewing the mixture, faulty fuel pressure regulator, weak fuel pump or clogged fuel filter.
• P0259 — P0259 — Injection Pump Fuel Metering Control B High (Cam/Rotor/Injector). A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: vacuum or intake leaks skewing the mixture, faulty fuel pressure regulator, weak fuel pump or clogged fuel filter.
• P025A — Fuel Pump Module Control Circuit/Open (P025A): 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 contaminated or incorrect fuel, vacuum or intake leaks skewing the mixture, faulty fuel pressure regulator.
• P025B — OBD2 code P025B flags a problem with the fuel delivery and mixture control (fuel pump module control circuit range/performance). Short, gentle driving to a shop is usually possible. Common culprits: contaminated or incorrect fuel, vacuum or intake leaks skewing the mixture, weak fuel pump or clogged fuel filter.
• P025C — Fuel Pump Module Control Circuit Low (P025C): 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 clogged or leaking fuel injectors, contaminated or incorrect fuel, vacuum or intake leaks skewing the mixture.
• P025D — P025D — Fuel Pump Module Control Circuit High. 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, contaminated or incorrect fuel, vacuum or intake leaks skewing the mixture.
• P0260 — Injection Pump Fuel Metering Control "B" Intermittent (Cam/Rotor/Injector) (P0260): 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 pressure regulator, vacuum or intake leaks skewing the mixture, contaminated or incorrect fuel.
• P0261 — OBD2 code P0261 flags a problem with the fuel delivery and mixture control (cylinder 1 injector circuit low). Short, gentle driving to a shop is usually possible. Common culprits: contaminated or incorrect fuel, faulty fuel rail pressure sensor or wiring, clogged or leaking fuel injectors.
• P0262 — P0262 — Cylinder 1 Injector Circuit High. 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, vacuum or intake leaks skewing the mixture.
• P0263 — P0263 — Cylinder 1 Contribution/Balance Fault. 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, faulty sensor or actuator of the affected circuit, poor ground connection.
• P0264 — Cylinder 2 Injector Circuit Low (P0264): 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, weak fuel pump or clogged fuel filter, contaminated or incorrect fuel.
• P0265 — Cylinder 2 Injector Circuit High (P0265): 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, vacuum or intake leaks skewing the mixture, clogged or leaking fuel injectors.
• P0266 — OBD2 code P0266 flags a problem with the sensor and actuator circuits (cylinder 2 contribution/balance fault). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit, poor ground connection.
• P0267 — Cylinder 3 Injector Circuit Low (P0267): 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, vacuum or intake leaks skewing the mixture.
• P0268 — OBD2 code P0268 flags a problem with the fuel delivery and mixture control (cylinder 3 injector circuit high). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, contaminated or incorrect fuel, faulty fuel rail pressure sensor or wiring.
• P0269 — Cylinder 3 Contribution/Balance Fault (P0269): 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, faulty sensor or actuator of the affected circuit.
• P0270 — P0270 — Cylinder 4 Injector Circuit Low. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: contaminated or incorrect fuel, clogged or leaking fuel injectors, faulty fuel pressure regulator.
• P0271 — Cylinder 4 Injector Circuit High (P0271): 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, vacuum or intake leaks skewing the mixture, contaminated or incorrect fuel.
• P0272 — P0272 — Cylinder 4 Contribution/Balance Fault. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: poor ground connection, faulty sensor or actuator of the affected circuit, control module driver fault.
• P0273 — OBD2 code P0273 flags a problem with the fuel delivery and mixture control (cylinder 5 injector circuit low). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel rail pressure sensor or wiring, vacuum or intake leaks skewing the mixture, faulty fuel pressure regulator.
• P0274 — P0274 — Cylinder 5 Injector Circuit High. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: contaminated or incorrect fuel, clogged or leaking fuel injectors, vacuum or intake leaks skewing the mixture.
• P0275 — OBD2 code P0275 flags a problem with the sensor and actuator circuits (cylinder 5 contribution/balance fault). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, poor ground connection, corroded, loose or damaged connector.
• P0276 — Cylinder 6 Injector Circuit Low (P0276): 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 contaminated or incorrect fuel, faulty fuel pressure regulator, weak fuel pump or clogged fuel filter.
• P0277 — OBD2 code P0277 flags a problem with the fuel delivery and mixture control (cylinder 6 injector circuit high). Short, gentle driving to a shop is usually possible. Common culprits: vacuum or intake leaks skewing the mixture, weak fuel pump or clogged fuel filter, clogged or leaking fuel injectors.