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

• P0174 — OBD2 code P0174 flags a problem with the sensor and actuator circuits (system too lean (bank 2)). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, control module driver fault, corroded, loose or damaged connector.
• P0175 — OBD2 code P0175 flags a problem with the sensor and actuator circuits (system too rich (bank 2)). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, poor ground connection, faulty sensor or actuator of the affected circuit.
• P0176 — P0176 — Fuel Composition Sensor Circuit Malfunction. 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, corroded, loose or damaged connector.
• P0177 — OBD2 code P0177 flags a problem with the sensor and actuator circuits (fuel composition sensor circuit range/performance). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, blown fuse feeding the circuit, control module driver fault.
• P0178 — Fuel Composition Sensor Circuit Low Input (P0178): 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, control module driver fault, open or shorted wiring in the circuit.
• P0179 — OBD2 code P0179 flags a problem with the sensor and actuator circuits (fuel composition sensor circuit high input). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, control module driver fault, poor ground connection.
• P0180 — Fuel Temperature Sensor A Circuit Malfunction (P0180): 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, open or shorted wiring in the circuit, poor ground connection.
• P0181 — P0181 — Fuel Temperature Sensor A Circuit 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, open or shorted wiring in the circuit, blown fuse feeding the circuit.
• P0182 — Fuel Temperature Sensor A Circuit Low Input (P0182): 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, corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit.
• P0183 — Fuel Temperature Sensor A Circuit High Input (P0183): 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, faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit.
• P0184 — P0184 — Fuel Temperature Sensor A Circuit Intermittent. 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, blown fuse feeding the circuit.
• P0185 — OBD2 code P0185 flags a problem with the sensor and actuator circuits (fuel temperature sensor b circuit malfunction). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, control module driver fault, blown fuse feeding the circuit.
• P0186 — P0186 — Fuel Temperature Sensor B Circuit Range/Performance. 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, control module driver fault, corroded, loose or damaged connector.
• P0187 — P0187 — Fuel Temperature Sensor B 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, faulty sensor or actuator of the affected circuit, control module driver fault.
• P0188 — P0188 — Fuel Temperature Sensor B Circuit High 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.
• P0189 — P0189 — Fuel Temperature Sensor B Circuit Intermittent. 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, blown fuse feeding the circuit.
• P018A — OBD2 code P018A flags a problem with the fuel delivery and mixture control (fuel pressure sensor "B" circuit). Short, gentle driving to a shop is usually possible. Common culprits: clogged or leaking fuel injectors, weak fuel pump or clogged fuel filter, contaminated or incorrect fuel.
• P018B — P018B — Fuel Pressure Sensor "B" Circuit Range/Performance. 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, clogged or leaking fuel injectors, faulty fuel pressure regulator.
• P018C — Fuel Pressure Sensor "B" Circuit Low (P018C): 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, faulty fuel rail pressure sensor or wiring.
• P018D — P018D — Fuel Pressure Sensor "B" 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, faulty fuel rail pressure sensor or wiring, faulty fuel pressure regulator.
• P018E — Fuel Pressure Sensor "B" Circuit Intermittent/Erratic (P018E): 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, clogged or leaking fuel injectors, weak fuel pump or clogged fuel filter.
• P018F — OBD2 code P018F flags a problem with the fuel delivery and mixture control (fuel system over pressure relief valve frequent activation). Short, gentle driving to a shop is usually possible. Common culprits: weak fuel pump or clogged fuel filter, clogged or leaking fuel injectors, contaminated or incorrect fuel.
• P0190 — Fuel Rail Pressure Sensor A Circuit (P0190): 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, clogged or leaking fuel injectors.
• P0191 — Fuel Rail Pressure Sensor A Circuit Range/Performance (P0191): 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, faulty fuel rail pressure sensor or wiring.