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

• U0153 — Lost Communication With Side Restraints Control Module Right (U0153): a vehicle network fault affecting the airbag / restraint system (SRS). Short, gentle driving to a shop is usually possible. Most often caused by failed clockspring (driver airbag circuit), faulty impact or occupancy sensor, damaged wiring under seats or in the steering column.
• U0154 — OBD2 code U0154 flags a problem with the airbag / restraint system (SRS) (lost communication with restraints occupant sensing control module). Short, gentle driving to a shop is usually possible. Common culprits: failed clockspring (driver airbag circuit), depleted backup battery or low system voltage, faulty impact or occupancy sensor.
• U0156 — Lost Communication With Information Center "A" (U0156): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by poor grounds or low battery voltage, damaged CAN bus wiring or short to power/ground, water ingress in harness junctions.
• U0157 — U0157 — Lost Communication With Information Center "B". A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: water ingress in harness junctions, a faulty module pulling the bus down, damaged CAN bus wiring or short to power/ground.
• U0158 — OBD2 code U0158 flags a problem with the vehicle network (CAN bus) communication (lost communication with head up display). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, aftermarket equipment interfering with the bus, a faulty module pulling the bus down.
• U0159 — U0159 — Lost Communication With Parking Assist Control Module "A". A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: poor grounds or low battery voltage, damaged CAN bus wiring or short to power/ground, water ingress in harness junctions.
• U0161 — OBD2 code U0161 flags a problem with the vehicle network (CAN bus) communication (lost communication with compass module). Short, gentle driving to a shop is usually possible. Common culprits: poor grounds or low battery voltage, aftermarket equipment interfering with the bus, damaged CAN bus wiring or short to power/ground.
• U0162 — OBD2 code U0162 flags a problem with the vehicle network (CAN bus) communication (lost communication with navigation display module). Short, gentle driving to a shop is usually possible. Common culprits: aftermarket equipment interfering with the bus, damaged CAN bus wiring or short to power/ground, poor grounds or low battery voltage.
• U0163 — Lost Communication With Navigation Control Module (U0163): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by damaged CAN bus wiring or short to power/ground, a faulty module pulling the bus down, water ingress in harness junctions.
• U0166 — Lost Communication With Auxiliary Heater Control Module (U0166): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by corroded connectors, especially in wet areas, poor grounds or low battery voltage, water ingress in harness junctions.
• U0168 — OBD2 code U0168 flags a problem with the vehicle network (CAN bus) communication (lost communication with vehicle security control module). Short, gentle driving to a shop is usually possible. Common culprits: water ingress in harness junctions, damaged CAN bus wiring or short to power/ground, aftermarket equipment interfering with the bus.
• U0169 — Lost Communication With Sunroof Control Module (U0169): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by a faulty module pulling the bus down, damaged CAN bus wiring or short to power/ground, water ingress in harness junctions.
• U016A — U016A — Lost Communication With Global Positioning System Module. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: damaged CAN bus wiring or short to power/ground, water ingress in harness junctions, a faulty module pulling the bus down.
• U0170 — U0170 — Lost Communication With Restraints System Sensor A. 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, faulty impact or occupancy sensor, damaged wiring under seats or in the steering column.
• U0171 — U0171 — Lost Communication With Restraints System Sensor B. 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, SRS control module fault or stored crash data, faulty impact or occupancy sensor.
• U0172 — Lost Communication With Restraints System Sensor C (U0172): a vehicle network 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, failed clockspring (driver airbag circuit), faulty impact or occupancy sensor.
• U0173 — OBD2 code U0173 flags a problem with the airbag / restraint system (SRS) (lost communication with restraints system sensor d). Short, gentle driving to a shop is usually possible. Common culprits: faulty impact or occupancy sensor, damaged wiring under seats or in the steering column, SRS control module fault or stored crash data.
• U0174 — OBD2 code U0174 flags a problem with the airbag / restraint system (SRS) (lost communication with restraints system sensor e). Short, gentle driving to a shop is usually possible. Common culprits: depleted backup battery or low system voltage, SRS control module fault or stored crash data, damaged wiring under seats or in the steering column.
• U0175 — OBD2 code U0175 flags a problem with the airbag / restraint system (SRS) (lost communication with restraints system sensor f). Short, gentle driving to a shop is usually possible. Common culprits: failed clockspring (driver airbag circuit), SRS control module fault or stored crash data, depleted backup battery or low system voltage.
• U0177 — U0177 — Lost Communication With Restraints System Sensor H. 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, SRS control module fault or stored crash data, faulty impact or occupancy sensor.
• U0178 — U0178 — Lost Communication With Restraints System Sensor I. A fault in the airbag / restraint system (SRS). Short, gentle driving to a shop is usually possible. Typical causes: SRS control module fault or stored crash data, faulty impact or occupancy sensor, failed clockspring (driver airbag circuit).
• U0179 — OBD2 code U0179 flags a problem with the airbag / restraint system (SRS) (lost communication with restraints system sensor j). Short, gentle driving to a shop is usually possible. Common culprits: faulty impact or occupancy sensor, SRS control module fault or stored crash data, depleted backup battery or low system voltage.
• U017A — U017A — Lost Communication With "Restraints System Sensor K". A fault in the airbag / restraint system (SRS). Short, gentle driving to a shop is usually possible. Typical causes: SRS control module fault or stored crash data, depleted backup battery or low system voltage, failed clockspring (driver airbag circuit).
• U017B — OBD2 code U017B flags a problem with the airbag / restraint system (SRS) (lost communication with "restraints system sensor L"). Short, gentle driving to a shop is usually possible. Common culprits: SRS control module fault or stored crash data, damaged wiring under seats or in the steering column, failed clockspring (driver airbag circuit).