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

• B2502 — B2502 — LF LAMP LOW BEAM CIRCUIT Short to Battery. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: corroded or loose connectors, blown fuse or failed relay, damaged wiring in door jambs or wet areas.
• B2503 — B2503 — RF LAMP LOW BEAM CIRCUIT Failure. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: body control module (BCM) fault, blown fuse or failed relay, faulty switch, motor or actuator of the affected system.
• B2504 — RF LAMP LOW BEAM CIRCUIT Short to Battery (B2504): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by faulty switch, motor or actuator of the affected system, corroded or loose connectors, damaged wiring in door jambs or wet areas.
• B2505 — B2505 — LF LAMP HIGH BEAM CIRCUIT Failure. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: damaged wiring in door jambs or wet areas, corroded or loose connectors, faulty switch, motor or actuator of the affected system.
• B2506 — B2506 — LF LAMP HIGH BEAM CIRCUIT Short to Battery. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: faulty switch, motor or actuator of the affected system, corroded or loose connectors, damaged wiring in door jambs or wet areas.
• B2507 — OBD2 code B2507 flags a problem with the body electrical system (RF LAMP HIGH BEAM CIRCUIT failure). The car is usually drivable while you plan the repair. Common culprits: faulty switch, motor or actuator of the affected system, blown fuse or failed relay, body control module (BCM) fault.
• B2508 — RF LAMP HIGH BEAM CIRCUIT Short to Battery (B2508): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by faulty switch, motor or actuator of the affected system, body control module (BCM) fault, corroded or loose connectors.
• B2509 — OBD2 code B2509 flags a problem with the body electrical system (rear fog lamp switch circuit failure). The car is usually drivable while you plan the repair. Common culprits: body control module (BCM) fault, faulty switch, motor or actuator of the affected system, corroded or loose connectors.
• B2510 — OBD2 code B2510 flags a problem with the body electrical system (main blower motor relay circuit short to battery). The car is usually drivable while you plan the repair. Common culprits: faulty switch, motor or actuator of the affected system, blown fuse or failed relay, damaged wiring in door jambs or wet areas.
• B2511 — OBD2 code B2511 flags a problem with the body electrical system (horn output relay circuit short to battery). The car is usually drivable while you plan the repair. Common culprits: damaged wiring in door jambs or wet areas, faulty switch, motor or actuator of the affected system, blown fuse or failed relay.
• B2512 — OBD2 code B2512 flags a problem with the body electrical system (front fog lamp relay ckt short to battery). The car is usually drivable while you plan the repair. Common culprits: blown fuse or failed relay, damaged wiring in door jambs or wet areas, faulty switch, motor or actuator of the affected system.
• B2513 — B2513 — Blower (Fan) Circuit Failure. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: body control module (BCM) fault, blown fuse or failed relay, faulty switch, motor or actuator of the affected system.
• B2514 — OBD2 code B2514 flags a problem with the body electrical system (blower (Fan) circuit short to vbatt). The car is usually drivable while you plan the repair. Common culprits: blown fuse or failed relay, damaged wiring in door jambs or wet areas, corroded or loose connectors.
• B2515 — OBD2 code B2515 flags a problem with the body electrical system (heater blower relay circuit failure). The car is usually drivable while you plan the repair. Common culprits: damaged wiring in door jambs or wet areas, corroded or loose connectors, blown fuse or failed relay.
• B2516 — OBD2 code B2516 flags a problem with the body electrical system (blower control circuit failure). The car is usually drivable while you plan the repair. Common culprits: damaged wiring in door jambs or wet areas, corroded or loose connectors, faulty switch, motor or actuator of the affected system.
• B2517 — Emergency Power Off System Faulted (B2517): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by corroded or loose connectors, damaged wiring in door jambs or wet areas, body control module (BCM) fault.
• B2518 — OBD2 code B2518 flags a problem with the body electrical system (compressor overtemp fault). The car is usually drivable while you plan the repair. Common culprits: corroded or loose connectors, body control module (BCM) fault, blown fuse or failed relay.
• B2519 — High Mount Stop Lamp Circuit Failure (B2519): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by faulty switch, motor or actuator of the affected system, corroded or loose connectors, damaged wiring in door jambs or wet areas.
• B2520 — B2520 — High Mount Stop Lamp Circuit Short to Battery. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: corroded or loose connectors, faulty switch, motor or actuator of the affected system, body control module (BCM) fault.
• B2523 — License Lamp Circuit Failure (B2523): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by body control module (BCM) fault, faulty switch, motor or actuator of the affected system, blown fuse or failed relay.
• B2524 — OBD2 code B2524 flags a problem with the body electrical system (license lamp circuit short to battery). The car is usually drivable while you plan the repair. Common culprits: corroded or loose connectors, blown fuse or failed relay, faulty switch, motor or actuator of the affected system.
• B2525 — OBD2 code B2525 flags a problem with the body electrical system (left rear backup lamp circuit failure). The car is usually drivable while you plan the repair. Common culprits: blown fuse or failed relay, damaged wiring in door jambs or wet areas, body control module (BCM) fault.
• B2526 — B2526 — Left Rear Backup Lamp Circuit Short to Battery. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: body control module (BCM) fault, faulty switch, motor or actuator of the affected system, corroded or loose connectors.
• B2527 — B2527 — Left Rear Stop lamp Circuit Failure. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: corroded or loose connectors, body control module (BCM) fault, blown fuse or failed relay.