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

• U1107 — U1107 — SCP (J1850) Invalid or Missing Data for Legislated Diagnostics. 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, damaged CAN bus wiring or short to power/ground, a faulty module pulling the bus down.
• U1108 — U1108 — SCP (J1850) Invalid or Missing Data for Electric Traction Drive (Inverter). A fault in the ABS / stability control. Short, gentle driving to a shop is usually possible. Typical causes: failed wheel speed sensor, blown fuse or low voltage to the ABS module, damaged sensor wiring or corroded connector.
• U1109 — U1109 — SCP (J1850) Invalid or Missing Data for Electric Traction Drive (Inverter). A fault in the ABS / stability control. Short, gentle driving to a shop is usually possible. Typical causes: damaged tone (reluctor) ring on the hub, blown fuse or low voltage to the ABS module, faulty ABS module or pump motor.
• U1110 — SCP (J1850) Invalid or Missing Data for Primary Id (U1110): 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, a faulty module pulling the bus down, aftermarket equipment interfering with the bus.
• U1111 — OBD2 code U1111 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for primary id). 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.
• U1112 — SCP (J1850) Invalid or Missing Data for Primary Id (U1112): 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, water ingress in harness junctions, damaged CAN bus wiring or short to power/ground.
• U1113 — SCP (J1850) Invalid or Missing Data for Primary Id (U1113): 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.
• U1114 — U1114 — SCP (J1850) Invalid or Missing Data for Charging System. 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, damaged CAN bus wiring or short to power/ground, a faulty module pulling the bus down.
• U1115 — SCP (J1850) Invalid or Missing Data for Charging System (U1115): 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, aftermarket equipment interfering with the bus, water ingress in harness junctions.
• U1116 — U1116 — SCP (J1850) Invalid or Missing Data for Electrical Energy Management. 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, aftermarket equipment interfering with the bus.
• U1118 — U1118 — SCP (J1850) Invalid or Missing Data for Primary Id. 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, a faulty module pulling the bus down, damaged CAN bus wiring or short to power/ground.
• U1119 — OBD2 code U1119 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for primary id). 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, water ingress in harness junctions.
• U1120 — U1120 — SCP (J1850) Invalid or Missing Data for Primary Id. 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, corroded connectors, especially in wet areas.
• U1121 — U1121 — SCP (J1850) Invalid or Missing Data for Primary Id. 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, corroded connectors, especially in wet areas, a faulty module pulling the bus down.
• U1123 — OBD2 code U1123 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for odometer). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, water ingress in harness junctions, aftermarket equipment interfering with the bus.
• U1124 — SCP (J1850) Invalid or Missing Data for Primary Id (U1124): 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.
• U1125 — SCP (J1850) Invalid or Missing Data for Primary Id (U1125): 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, water ingress in harness junctions, poor grounds or low battery voltage.
• U1126 — OBD2 code U1126 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for primary id). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, poor grounds or low battery voltage, water ingress in harness junctions.
• U1127 — SCP (J1850) Invalid or Missing Data for Primary Id (U1127): 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, damaged CAN bus wiring or short to power/ground.
• U1128 — SCP (J1850) Invalid or Missing Data for Primary Id (U1128): 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, aftermarket equipment interfering with the bus, damaged CAN bus wiring or short to power/ground.
• U1129 — U1129 — SCP (J1850) Invalid or Missing Data for Primary Id. 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, aftermarket equipment interfering with the bus.
• U1130 — OBD2 code U1130 flags a problem with the fuel delivery and mixture control (SCP (J1850) invalid or missing data for fuel system). Short, gentle driving to a shop is usually possible. Common culprits: vacuum or intake leaks skewing the mixture, contaminated or incorrect fuel, weak fuel pump or clogged fuel filter.
• U1131 — OBD2 code U1131 flags a problem with the fuel delivery and mixture control (SCP (J1850) invalid or missing data for fuel system). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, clogged or leaking fuel injectors, vacuum or intake leaks skewing the mixture.
• U1132 — U1132 — SCP (J1850) Invalid or Missing Data for Vehicle Motion. 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, corroded connectors, especially in wet areas, poor grounds or low battery voltage.