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

• B1800 — OBD2 code B1800 flags a problem with the body electrical system (lamp turn signal front output circuit short to battery). The car is usually drivable while you plan the repair. Common culprits: corroded or loose connectors, faulty switch, motor or actuator of the affected system, damaged wiring in door jambs or wet areas.
• B1801 — OBD2 code B1801 flags a problem with the body electrical system (lamp turn signal front output circuit short to ground). The car is usually drivable while you plan the repair. Common culprits: blown fuse or failed relay, faulty switch, motor or actuator of the affected system, damaged wiring in door jambs or wet areas.
• B1802 — Lamp Turn Signal Rear Output Circuit Failure (B1802): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by blown fuse or failed relay, body control module (BCM) fault, corroded or loose connectors.
• B1803 — OBD2 code B1803 flags a problem with the body electrical system (lamp turn signal rear output circuit open). 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.
• B1804 — B1804 — Lamp Turn Signal Rear Output 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, body control module (BCM) fault.
• B1805 — B1805 — Lamp Turn Signal Rear Output Circuit Short To Ground. 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, damaged wiring in door jambs or wet areas, body control module (BCM) fault.
• B1806 — OBD2 code B1806 flags a problem with the body electrical system (lamp tail output 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, damaged wiring in door jambs or wet areas.
• B1807 — Lamp Tail Output Circuit Open (B1807): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by blown fuse or failed relay, damaged wiring in door jambs or wet areas, corroded or loose connectors.
• B1808 — B1808 — Lamp Tail Output 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, blown fuse or failed relay.
• B1809 — B1809 — Lamp Tail Output Circuit Short To Ground. 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, body control module (BCM) fault, corroded or loose connectors.
• B1810 — OBD2 code B1810 flags a problem with the body electrical system (lamp backup switch input circuit failure). The car is usually drivable while you plan the repair. Common culprits: blown fuse or failed relay, body control module (BCM) fault, corroded or loose connectors.
• B1811 — Lamp Backup Switch Input Circuit Open (B1811): 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, body control module (BCM) fault, blown fuse or failed relay.
• B1812 — OBD2 code B1812 flags a problem with the body electrical system (lamp backup switch input circuit short to battery). The car is usually drivable while you plan the repair. Common culprits: corroded or loose connectors, damaged wiring in door jambs or wet areas, faulty switch, motor or actuator of the affected system.
• B1813 — OBD2 code B1813 flags a problem with the body electrical system (lamp backup switch input circuit short to ground). The car is usually drivable while you plan the repair. Common culprits: body control module (BCM) fault, blown fuse or failed relay, faulty switch, motor or actuator of the affected system.
• B1814 — B1814 — Wiper Rear Motor Down Relay Coil Circuit Failure. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: failed ignition coil or coil pack, faulty ignition control circuit in the ECM, worn spark plugs or wrong plug gap.
• B1815 — OBD2 code B1815 flags a problem with the ignition system (wiper rear motor down relay coil circuit open). Short, gentle driving to a shop is usually possible. Common culprits: failed ignition coil or coil pack, worn spark plugs or wrong plug gap, faulty ignition control circuit in the ECM.
• B1816 — B1816 — Wiper Rear Motor Down Relay Coil Circuit Short To Battery. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: worn spark plugs or wrong plug gap, damaged coil wiring or connector, failed ignition coil or coil pack.
• B1817 — B1817 — Wiper Rear Motor Down Relay Coil Circuit Short To Ground. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: failed ignition coil or coil pack, worn spark plugs or wrong plug gap, faulty ignition control circuit in the ECM.
• B1818 — OBD2 code B1818 flags a problem with the ignition system (wiper rear motor up relay coil circuit failure). Short, gentle driving to a shop is usually possible. Common culprits: failed ignition coil or coil pack, moisture or oil in the spark plug wells, faulty ignition control circuit in the ECM.
• B1819 — OBD2 code B1819 flags a problem with the ignition system (wiper rear motor up relay coil circuit open). Short, gentle driving to a shop is usually possible. Common culprits: faulty ignition control circuit in the ECM, failed ignition coil or coil pack, moisture or oil in the spark plug wells.
• B1820 — Wiper Rear Motor Up Relay Coil Circuit Short To Battery (B1820): a body electrical fault affecting the ignition system. Short, gentle driving to a shop is usually possible. Most often caused by failed ignition coil or coil pack, worn spark plugs or wrong plug gap, faulty ignition control circuit in the ECM.
• B1821 — B1821 — Wiper Rear Motor Up Relay Coil Circuit Short To Ground. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: faulty ignition control circuit in the ECM, failed ignition coil or coil pack, worn spark plugs or wrong plug gap.
• B1822 — Wiper Rear Park Sense Input Circuit Failure (B1822): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by blown fuse or failed relay, corroded or loose connectors, faulty switch, motor or actuator of the affected system.
• B1823 — B1823 — Wiper Rear Park Sense Input Circuit Open. 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, blown fuse or failed relay, faulty switch, motor or actuator of the affected system.