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

• B1848 — OBD2 code B1848 flags a problem with the ignition system (ignition tamper circuit short to ground). Short, gentle driving to a shop is usually possible. Common culprits: worn spark plugs or wrong plug gap, failed ignition coil or coil pack, faulty ignition control circuit in the ECM.
• B1849 — OBD2 code B1849 flags a problem with the body electrical system (climate control temperature differential circuit failure). The car is usually drivable while you plan the repair. Common culprits: damaged wiring in door jambs or wet areas, blown fuse or failed relay, faulty switch, motor or actuator of the affected system.
• B1850 — B1850 — Climate Control Temperature Differential 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, corroded or loose connectors, blown fuse or failed relay.
• B1851 — OBD2 code B1851 flags a problem with the body electrical system (climate control temperature differential 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.
• B1852 — Climate Control Temperature Differential Circuit Short To Ground (B1852): 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, faulty switch, motor or actuator of the affected system, corroded or loose connectors.
• B1853 — OBD2 code B1853 flags a problem with the body electrical system (climate control air temperature internal sensor motor circuit failure). 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, body control module (BCM) fault.
• B1854 — OBD2 code B1854 flags a problem with the body electrical system (climate control air temperature internal sensor motor circuit open). 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.
• B1855 — OBD2 code B1855 flags a problem with the body electrical system (climate control air temperature internal sensor motor circuit short to battery). The car is usually drivable while you plan the repair. Common culprits: damaged wiring in door jambs or wet areas, blown fuse or failed relay, corroded or loose connectors.
• B1856 — Climate Control Air Temperature Internal Sensor Motor Circuit Short To Ground (B1856): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by damaged wiring in door jambs or wet areas, body control module (BCM) fault, corroded or loose connectors.
• B1857 — B1857 — Climate Control On/Off Switch 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, damaged wiring in door jambs or wet areas, blown fuse or failed relay.
• B1858 — OBD2 code B1858 flags a problem with the body electrical system (climate control A/C pressure switch circuit failure). The car is usually drivable while you plan the repair. Common culprits: body control module (BCM) fault, damaged wiring in door jambs or wet areas, blown fuse or failed relay.
• B1859 — Climate Control A/C Pressure Switch Circuit Open (B1859): 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, damaged wiring in door jambs or wet areas, corroded or loose connectors.
• B1860 — OBD2 code B1860 flags a problem with the body electrical system (climate control A/C pressure switch 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, damaged wiring in door jambs or wet areas, body control module (BCM) fault.
• B1861 — B1861 — Climate Control A/C Pressure Switch Circuit Short To Ground. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: body control module (BCM) fault, damaged wiring in door jambs or wet areas, faulty switch, motor or actuator of the affected system.
• B1862 — B1862 — Climate Control A/C Lock Sensor Failure. 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, body control module (BCM) fault.
• B1863 — B1863 — Ground ECU Circuit Open. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: blown fuse or failed relay, damaged wiring in door jambs or wet areas, corroded or loose connectors.
• B1864 — Battery Power Supply ECU Circuit Failure (B1864): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by damaged wiring in door jambs or wet areas, corroded or loose connectors, body control module (BCM) fault.
• B1865 — B1865 — Battery Power Supply ECU Circuit Open. 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, damaged wiring in door jambs or wet areas.
• B1866 — OBD2 code B1866 flags a problem with the body electrical system (battery power supply ECU circuit short to battery). The car is usually drivable while you plan the repair. Common culprits: blown fuse or failed relay, body control module (BCM) fault, damaged wiring in door jambs or wet areas.
• B1867 — B1867 — Battery Power Supply ECU 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, damaged wiring in door jambs or wet areas.
• B1868 — B1868 — Lamp Air Bag Warning Indicator Circuit Failure. A fault in the airbag / restraint system (SRS). Short, gentle driving to a shop is usually possible. Typical causes: faulty impact or occupancy sensor, depleted backup battery or low system voltage, failed clockspring (driver airbag circuit).
• B1869 — B1869 — Lamp Air Bag Warning Indicator Circuit Open. A fault in the airbag / restraint system (SRS). Short, gentle driving to a shop is usually possible. Typical causes: depleted backup battery or low system voltage, damaged wiring under seats or in the steering column, SRS control module fault or stored crash data.
• B1870 — OBD2 code B1870 flags a problem with the airbag / restraint system (SRS) (lamp air bag warning indicator circuit short to battery). Short, gentle driving to a shop is usually possible. Common culprits: failed clockspring (driver airbag circuit), faulty impact or occupancy sensor, depleted backup battery or low system voltage.
• B1871 — Passenger Air Bag Disable Module Fault (B1871): a body electrical fault affecting the airbag / restraint system (SRS). Short, gentle driving to a shop is usually possible. Most often caused by depleted backup battery or low system voltage, SRS control module fault or stored crash data, failed clockspring (driver airbag circuit).