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.

P254A — OBD2 code P254A flags a problem with the sensor and actuator circuits (PTO speed selector sensor/switch 1 circuit/open). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, control module driver fault, corroded, loose or damaged connector.
P254B — PTO Speed Selector Sensor/Switch 1 Range/Performance (P254B): 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, corroded, loose or damaged connector.
P254C — PTO Speed Selector Sensor/Switch 1 Circuit Low (P254C): 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, open or shorted wiring in the circuit.
P254D — P254D — PTO Speed Selector Sensor/Switch 1 Circuit High. 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, poor ground connection.
P254E — OBD2 code P254E flags a problem with the sensor and actuator circuits (PTO speed selector sensor/switch 1 circuit intermittent/erratic). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit, poor ground connection.
P254F — OBD2 code P254F flags a problem with the sensor and actuator circuits (engine hood switch circuit). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, poor ground connection, blown fuse feeding the circuit.
P2551 — Torque Management Request Input Signal "B" High (P2551): 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, control module driver fault, poor ground connection.
P2552 — OBD2 code P2552 flags a problem with the throttle and intake air metering (throttle/fuel inhibit circuit). Short, gentle driving to a shop is usually possible. Common culprits: dirty throttle body or stuck throttle plate, intake air leaks after the MAF sensor, failed electronic throttle motor.
P2553 — P2553 — Throttle/Fuel Inhibit Circuit Range/Performance. A fault in the throttle and intake air metering. Short, gentle driving to a shop is usually possible. Typical causes: failed electronic throttle motor, intake air leaks after the MAF sensor, dirty throttle body or stuck throttle plate.
P2555 — P2555 — Throttle/Fuel Inhibit Circuit High. A fault in the throttle and intake air metering. Short, gentle driving to a shop is usually possible. Typical causes: dirty throttle body or stuck throttle plate, wiring or connector faults in the throttle circuit, faulty throttle position sensor or pedal sensor.
P2556 — P2556 — Engine Coolant Level Sensor/Switch Circuit. A fault in the engine cooling and temperature control. Short, gentle driving to a shop is usually possible. Typical causes: wiring faults in the sensor circuit, low coolant level or air in the system, failed cooling fan or fan relay.
P2558 — P2558 — Engine Coolant Level Sensor/Switch Circuit Low. A fault in the engine cooling and temperature control. Short, gentle driving to a shop is usually possible. Typical causes: thermostat stuck open or closed, water pump or radiator issues, failed cooling fan or fan relay.
P255A — PTO Speed Selector Sensor/Switch 2 Circuit/Open (P255A): 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, open or shorted wiring in the circuit.
P255B — OBD2 code P255B flags a problem with the sensor and actuator circuits (PTO speed selector sensor/switch 2 range/performance). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit, open or shorted wiring in the circuit.
P255C — OBD2 code P255C flags a problem with the sensor and actuator circuits (PTO speed selector sensor/switch 2 circuit low). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit.
P255D — PTO Speed Selector Sensor/Switch 2 Circuit High (P255D): 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, blown fuse feeding the circuit.
P255E — OBD2 code P255E flags a problem with the sensor and actuator circuits (PTO speed selector sensor/switch 2 circuit intermittent/erratic). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, open or shorted wiring in the circuit, poor ground connection.
P255F — P255F — A/C Request "A" Circuit Range/Performance. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: control module driver fault, poor ground connection, corroded, loose or damaged connector.
P2560 — Engine Coolant Level Low (P2560): a powertrain (engine/transmission) fault affecting the engine cooling and temperature control. Short, gentle driving to a shop is usually possible. Most often caused by low coolant level or air in the system, thermostat stuck open or closed, failed cooling fan or fan relay.
P2561 — OBD2 code P2561 flags a problem with the sensor and actuator circuits (A/C control module requested MIL illumination). 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.
P2562 — Turbocharger Boost Control Position Sensor "A" Circuit (P2562): 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, faulty boost pressure sensor, clogged intake or exhaust (DPF/cat).
P2564 — P2564 — Turbocharger Boost Control Position Sensor "A" Circuit Low. A fault in the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Typical causes: worn turbocharger, stuck wastegate or faulty boost control solenoid, vacuum or actuator line damage.
P2565 — Turbocharger Boost Control Position Sensor "A" Circuit High (P2565): 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), stuck wastegate or faulty boost control solenoid, boost leak in intercooler piping or hoses.
P2566 — OBD2 code P2566 flags a problem with the turbocharger / supercharger boost control (turbocharger boost control position sensor "A" circuit intermittent). Short, gentle driving to a shop is usually possible. Common culprits: worn turbocharger, boost leak in intercooler piping or hoses, clogged intake or exhaust (DPF/cat).