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

• U0068 — Vehicle Communication Bus E (+) High (U0068): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by water ingress in harness junctions, a faulty module pulling the bus down, poor grounds or low battery voltage.
• U0069 — OBD2 code U0069 flags a problem with the vehicle network (CAN bus) communication (vehicle communication bus e (-) open). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, damaged CAN bus wiring or short to power/ground, a faulty module pulling the bus down.
• U0070 — OBD2 code U0070 flags a problem with the vehicle network (CAN bus) communication (vehicle communication bus e (-) low). Short, gentle driving to a shop is usually possible. Common culprits: a faulty module pulling the bus down, aftermarket equipment interfering with the bus, water ingress in harness junctions.
• U0071 — Vehicle Communication Bus E (-) High (U0071): 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, damaged CAN bus wiring or short to power/ground, water ingress in harness junctions.
• U0072 — U0072 — Vehicle Communication Bus E (-) shorted to Bus E (+). 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, water ingress in harness junctions, damaged CAN bus wiring or short to power/ground.
• U0074 — OBD2 code U0074 flags a problem with the vehicle network (CAN bus) communication (control module communication bus b off). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, poor grounds or low battery voltage, aftermarket equipment interfering with the bus.
• U0075 — OBD2 code U0075 flags a problem with the vehicle network (CAN bus) communication (U0075 - control module communication bus b off). Short, gentle driving to a shop is usually possible. Common culprits: a faulty module pulling the bus down, aftermarket equipment interfering with the bus, poor grounds or low battery voltage.
• U0076 — OBD2 code U0076 flags a problem with the vehicle network (CAN bus) communication (U0076 - control module communication bus c off). Short, gentle driving to a shop is usually possible. Common culprits: poor grounds or low battery voltage, aftermarket equipment interfering with the bus, water ingress in harness junctions.
• U0077 — U0077 — U0077 - Control Module Communication Bus D Off. 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, a faulty module pulling the bus down, corroded connectors, especially in wet areas.
• U0079 — U0079 - Control Module Communication Bus F Off (U0079): a vehicle fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by water ingress in harness junctions, aftermarket equipment interfering with the bus, poor grounds or low battery voltage.
• U0080 — OBD2 code U0080 flags a problem with the vehicle network (CAN bus) communication (U0080 - control module communication bus g off). 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, corroded connectors, especially in wet areas.
• U0081 — U0081 - Control Module Communication Bus H Off (U0081): a vehicle 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.
• U0082 — OBD2 code U0082 flags a problem with the vehicle network (CAN bus) communication (U0082 - control module communication bus i off). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, water ingress in harness junctions, damaged CAN bus wiring or short to power/ground.
• U0083 — OBD2 code U0083 flags a problem with the vehicle network (CAN bus) communication (U0083 - control module communication bus j off). Short, gentle driving to a shop is usually possible. Common culprits: poor grounds or low battery voltage, a faulty module pulling the bus down, aftermarket equipment interfering with the bus.
• U0084 — U0084 - Control Module Communication Bus K Off (U0084): a vehicle 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, corroded connectors, especially in wet areas, poor grounds or low battery voltage.
• U0085 — U0085 — U0085 - Control Module Communication Bus L Off. 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.
• U0086 — OBD2 code U0086 flags a problem with the vehicle network (CAN bus) communication (U0086 - control module communication bus m off). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, a faulty module pulling the bus down, damaged CAN bus wiring or short to power/ground.
• U0087 — U0087 — U0087 - Control Module Communication Bus N Off. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: aftermarket equipment interfering with the bus, water ingress in harness junctions, damaged CAN bus wiring or short to power/ground.
• U0089 — OBD2 code U0089 flags a problem with the vehicle network (CAN bus) communication (U0089 - control module communication bus p off). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, damaged CAN bus wiring or short to power/ground, a faulty module pulling the bus down.
• U0090 — OBD2 code U0090 flags a problem with the vehicle network (CAN bus) communication (U0090 - control module communication bus q off). Short, gentle driving to a shop is usually possible. Common culprits: a faulty module pulling the bus down, water ingress in harness junctions, poor grounds or low battery voltage.
• U0091 — U0091 — U0091 - Control Module Communication Bus R Off. 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, poor grounds or low battery voltage.
• U0092 — U0092 — U0092 - Control Module Communication Bus S Off. 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, poor grounds or low battery voltage, aftermarket equipment interfering with the bus.
• U0093 — U0093 — U0093 - Control Module Communication Bus T Off. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: aftermarket equipment interfering with the bus, corroded connectors, especially in wet areas, water ingress in harness junctions.
• U0094 — OBD2 code U0094 flags a problem with the vehicle network (CAN bus) communication (U0094 - control module communication bus u off). Short, gentle driving to a shop is usually possible. Common culprits: damaged CAN bus wiring or short to power/ground, water ingress in harness junctions, corroded connectors, especially in wet areas.