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

• U0042 — OBD2 code U0042 flags a problem with the vehicle network (CAN bus) communication (vehicle communication bus b (-) open). Short, gentle driving to a shop is usually possible. Common culprits: damaged CAN bus wiring or short to power/ground, a faulty module pulling the bus down, poor grounds or low battery voltage.
• U0043 — U0043 — Vehicle Communication Bus B (-) Low. 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, damaged CAN bus wiring or short to power/ground.
• U0044 — U0044 — Vehicle Communication Bus B (-) High. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: a faulty module pulling the bus down, corroded connectors, especially in wet areas, aftermarket equipment interfering with the bus.
• U0045 — U0045 — Vehicle Communication Bus B (-) shorted to Bus B (+). A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: a faulty module pulling the bus down, aftermarket equipment interfering with the bus, water ingress in harness junctions.
• U0047 — Vehicle Communication Bus C Performance (U0047): 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, damaged CAN bus wiring or short to power/ground, corroded connectors, especially in wet areas.
• U0048 — OBD2 code U0048 flags a problem with the vehicle network (CAN bus) communication (vehicle communication bus c (+) open). Short, gentle driving to a shop is usually possible. Common culprits: water ingress in harness junctions, corroded connectors, especially in wet areas, damaged CAN bus wiring or short to power/ground.
• U0049 — OBD2 code U0049 flags a problem with the vehicle network (CAN bus) communication (vehicle communication bus c (+) low). 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, aftermarket equipment interfering with the bus.
• U0050 — U0050 — Vehicle Communication Bus C (+) High. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: corroded connectors, especially in wet areas, poor grounds or low battery voltage, water ingress in harness junctions.
• U0051 — OBD2 code U0051 flags a problem with the vehicle network (CAN bus) communication (vehicle communication bus c (-) open). 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.
• U0052 — OBD2 code U0052 flags a problem with the vehicle network (CAN bus) communication (vehicle communication bus c (-) low). 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, a faulty module pulling the bus down.
• U0053 — Vehicle Communication Bus C (-) High (U0053): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by aftermarket equipment interfering with the bus, damaged CAN bus wiring or short to power/ground, poor grounds or low battery voltage.
• U0054 — Vehicle Communication Bus C (-) shorted to Bus C (+) (U0054): 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, poor grounds or low battery voltage, a faulty module pulling the bus down.
• U0055 — Vehicle Communication Bus D (U0055): 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, poor grounds or low battery voltage.
• U0056 — U0056 — Vehicle Communication Bus D Performance. 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.
• U0057 — OBD2 code U0057 flags a problem with the vehicle network (CAN bus) communication (vehicle communication bus d (+) open). Short, gentle driving to a shop is usually possible. Common culprits: water ingress in harness junctions, aftermarket equipment interfering with the bus, damaged CAN bus wiring or short to power/ground.
• U0058 — OBD2 code U0058 flags a problem with the vehicle network (CAN bus) communication (vehicle communication bus d (+) low). Short, gentle driving to a shop is usually possible. Common culprits: water ingress in harness junctions, corroded connectors, especially in wet areas, damaged CAN bus wiring or short to power/ground.
• U0059 — Vehicle Communication Bus D (+) High (U0059): 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, poor grounds or low battery voltage, corroded connectors, especially in wet areas.
• U0060 — OBD2 code U0060 flags a problem with the vehicle network (CAN bus) communication (vehicle communication bus d (-) open). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, poor grounds or low battery voltage, a faulty module pulling the bus down.
• U0061 — Vehicle Communication Bus D (-) Low (U0061): 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, poor grounds or low battery voltage.
• U0062 — Vehicle Communication Bus D (-) High (U0062): 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, poor grounds or low battery voltage.
• U0063 — OBD2 code U0063 flags a problem with the vehicle network (CAN bus) communication (vehicle communication bus d (-) shorted to bus d (+)). Short, gentle driving to a shop is usually possible. Common culprits: poor grounds or low battery voltage, water ingress in harness junctions, corroded connectors, especially in wet areas.
• U0065 — U0065 — Vehicle Communication Bus E Performance. 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, a faulty module pulling the bus down.
• U0066 — OBD2 code U0066 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: damaged CAN bus wiring or short to power/ground, water ingress in harness junctions, corroded connectors, especially in wet areas.
• U0067 — OBD2 code U0067 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: damaged CAN bus wiring or short to power/ground, water ingress in harness junctions, aftermarket equipment interfering with the bus.