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.

P2239 — P2239 — O2 Sensor Positive Current Control Circuit High Bank 1 Sensor 1. A fault in the oxygen sensor circuit. The car is usually drivable while you plan the repair. Typical causes: aged or contaminated oxygen sensor, ECM signal circuit fault, blown sensor heater fuse.
P2240 — O2 Sensor Positive Current Control Circuit/Open Bank 2 Sensor 1 (P2240): a powertrain (engine/transmission) fault affecting the oxygen sensor circuit. The car is usually drivable while you plan the repair. Most often caused by aged or contaminated oxygen sensor, exhaust leak near the sensor, blown sensor heater fuse.
P2242 — OBD2 code P2242 flags a problem with the oxygen sensor circuit (O2 sensor positive current control circuit high bank 2 sensor 1). The car is usually drivable while you plan the repair. Common culprits: exhaust leak near the sensor, damaged sensor wiring or connector, blown sensor heater fuse.
P2243 — P2243 — O2 Sensor Reference Voltage Circuit/Open Bank 1 Sensor 1. A fault in the oxygen sensor circuit. The car is usually drivable while you plan the repair. Typical causes: aged or contaminated oxygen sensor, damaged sensor wiring or connector, ECM signal circuit fault.
P2244 — P2244 — O2 Sensor Reference Voltage Performance Bank 1 Sensor 1. A fault in the oxygen sensor circuit. The car is usually drivable while you plan the repair. Typical causes: damaged sensor wiring or connector, oil or coolant contamination of the sensor tip, exhaust leak near the sensor.
P2245 — P2245 — O2 Sensor Reference Voltage Circuit Low Bank 1 Sensor 1. A fault in the oxygen sensor circuit. The car is usually drivable while you plan the repair. Typical causes: damaged sensor wiring or connector, exhaust leak near the sensor, oil or coolant contamination of the sensor tip.
P2246 — O2 Sensor Reference Voltage Circuit High Bank 1 Sensor 1 (P2246): a powertrain (engine/transmission) fault affecting the oxygen sensor circuit. The car is usually drivable while you plan the repair. Most often caused by ECM signal circuit fault, aged or contaminated oxygen sensor, exhaust leak near the sensor.
P2247 — P2247 — O2 Sensor Reference Voltage Circuit/Open Bank 2 Sensor 1. A fault in the oxygen sensor circuit. The car is usually drivable while you plan the repair. Typical causes: exhaust leak near the sensor, oil or coolant contamination of the sensor tip, damaged sensor wiring or connector.
P2248 — P2248 — O2 Sensor Reference Voltage Performance Bank 2 Sensor 1. A fault in the oxygen sensor circuit. The car is usually drivable while you plan the repair. Typical causes: aged or contaminated oxygen sensor, exhaust leak near the sensor, damaged sensor wiring or connector.
P2249 — O2 Sensor Reference Voltage Circuit Low Bank 2 Sensor 1 (P2249): a powertrain (engine/transmission) fault affecting the oxygen sensor circuit. The car is usually drivable while you plan the repair. Most often caused by aged or contaminated oxygen sensor, blown sensor heater fuse, damaged sensor wiring or connector.
P2250 — OBD2 code P2250 flags a problem with the oxygen sensor circuit (O2 sensor reference voltage circuit high bank 2 sensor 1). The car is usually drivable while you plan the repair. Common culprits: aged or contaminated oxygen sensor, exhaust leak near the sensor, blown sensor heater fuse.
P2251 — O2 Sensor Negative Current Control Circuit/Open Bank 1 Sensor 1 (P2251): a powertrain (engine/transmission) fault affecting the oxygen sensor circuit. The car is usually drivable while you plan the repair. Most often caused by oil or coolant contamination of the sensor tip, blown sensor heater fuse, aged or contaminated oxygen sensor.
P2252 — OBD2 code P2252 flags a problem with the oxygen sensor circuit (O2 sensor negative current control circuit low bank 1 sensor 1). The car is usually drivable while you plan the repair. Common culprits: blown sensor heater fuse, oil or coolant contamination of the sensor tip, exhaust leak near the sensor.
P2253 — O2 Sensor Negative Current Control Circuit High Bank 1 Sensor 1 (P2253): a powertrain (engine/transmission) fault affecting the oxygen sensor circuit. The car is usually drivable while you plan the repair. Most often caused by damaged sensor wiring or connector, aged or contaminated oxygen sensor, oil or coolant contamination of the sensor tip.
P2254 — O2 Sensor Negative Current Control Circuit/Open Bank 2 Sensor 1 (P2254): a powertrain (engine/transmission) fault affecting the oxygen sensor circuit. The car is usually drivable while you plan the repair. Most often caused by ECM signal circuit fault, blown sensor heater fuse, damaged sensor wiring or connector.
P2255 — P2255 — O2 Sensor Negative Current Control Circuit Low Bank 2 Sensor 1. A fault in the oxygen sensor circuit. The car is usually drivable while you plan the repair. Typical causes: aged or contaminated oxygen sensor, exhaust leak near the sensor, oil or coolant contamination of the sensor tip.
P2256 — P2256 — O2 Sensor Negative Current Control Circuit High Bank 2 Sensor 1. A fault in the oxygen sensor circuit. The car is usually drivable while you plan the repair. Typical causes: damaged sensor wiring or connector, oil or coolant contamination of the sensor tip, exhaust leak near the sensor.
P2257 — Secondary Air Injection System Control "A" Circuit Low (P2257): 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, control module driver fault.
P2258 — Secondary Air Injection System Control "A" Circuit High (P2258): 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 open or shorted wiring in the circuit, corroded, loose or damaged connector, blown fuse feeding the circuit.
P2259 — Secondary Air Injection System Control "B" Circuit Low (P2259): 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 open or shorted wiring in the circuit, faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit.
P2260 — OBD2 code P2260 flags a problem with the sensor and actuator circuits (secondary air injection system control "B" circuit high). 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.
P2261 — P2261 — Turbocharger/Supercharger Bypass Valve - Mechanical. 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, vacuum or actuator line damage.
P2266 — P2266 — Water in Fuel Sensor Circuit Low. 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, control module driver fault.
P2268 — OBD2 code P2268 flags a problem with the sensor and actuator circuits (water in fuel sensor circuit intermittent). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, open or shorted wiring in the circuit, poor ground connection.