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.

C1117 — OBD2 code C1117 flags a problem with the sensor and actuator circuits (RPM input circuit failure). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, open or shorted wiring in the circuit, corroded, loose or damaged connector.
C1120 — C1120 — C1120 — Traction Control Module Communication Error: Causes, Symptoms & Fix. A fault in the ABS / stability control. Short, gentle driving to a shop is usually possible. Typical causes: faulty ABS module or pump motor, failed wheel speed sensor, damaged tone (reluctor) ring on the hub.
C1121 — OBD2 code C1121 flags a problem with the sensor and actuator circuits (C1121 — airmatic fault in component B24/3 acceleration sensor: causes, symptoms & fix). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit, corroded, loose or damaged connector.
C1122 — C1122 — AIRmatic Fault in Component B24/4 Acceleration Sensor: Causes, Symptoms & Fix (C1122): a vehicle fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by poor ground connection, control module driver fault, faulty sensor or actuator of the affected circuit.
C1123 — OBD2 code C1123 flags a problem with the sensor and actuator circuits (vehicle speed sensor input short to battery). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, corroded, loose or damaged connector, blown fuse feeding the circuit.
C1124 — OBD2 code C1124 flags a problem with the sensor and actuator circuits (input shaft speed signal missing/faulted). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, faulty sensor or actuator of the affected circuit, open or shorted wiring in the circuit.
C1125 — C1125 — Brake Fluid Level Sensor Input Circuit Failure. A fault in the ABS / stability control. Short, gentle driving to a shop is usually possible. Typical causes: failed wheel speed sensor, damaged tone (reluctor) ring on the hub, blown fuse or low voltage to the ABS module.
C1126 — C1126 — Cruise Control Command Switch Assembly Circuit Failure. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: blown fuse feeding the circuit, control module driver fault, poor ground connection.
C1127 — C1127 — Cruise Control Deactivator Brake Switch Circuit Failure. A fault in the ABS / stability control. Short, gentle driving to a shop is usually possible. Typical causes: failed wheel speed sensor, damaged tone (reluctor) ring on the hub, damaged sensor wiring or corroded connector.
C1130 — OBD2 code C1130 flags a problem with the ABS / stability control (C1130 — electronic stability control module communication fault: causes, symptoms & fix). Short, gentle driving to a shop is usually possible. Common culprits: damaged sensor wiring or corroded connector, failed wheel speed sensor, damaged tone (reluctor) ring on the hub.
C1132 — Clutch position ckt short to ground (C1132): a chassis (brakes/steering/suspension) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by corroded, loose or damaged connector, blown fuse feeding the circuit, poor ground connection.
C1133 — Clutch position ckt short to battery (C1133): a chassis (brakes/steering/suspension) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by open or shorted wiring in the circuit, corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit.
C1134 — OBD2 code C1134 flags a problem with the automatic transmission control (gear shift position short to ground). Short, gentle driving to a shop is usually possible. Common culprits: low or degraded transmission fluid, failed shift or pressure control solenoid, internal mechanical wear (clutches, torque converter).
C1135 — Gear Shift position short to battery (C1135): a chassis (brakes/steering/suspension) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by faulty transmission speed sensor, valve body wear, internal mechanical wear (clutches, torque converter).
C1136 — Gear Select position short to ground (C1136): a chassis (brakes/steering/suspension) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by poor ground connection, blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit.
C1137 — ECU is Defective (C1137): a chassis (brakes/steering/suspension) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit, poor ground connection.
C1138 — C1138 — Gear Select position short to Battery. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: corroded, loose or damaged connector, poor ground connection, faulty sensor or actuator of the affected circuit.
C1139 — Wheel Speed Sensor Center Tone Ring Missing Tooth Fault (C1139): a chassis (brakes/steering/suspension) fault affecting the ABS / stability control. Short, gentle driving to a shop is usually possible. Most often caused by faulty ABS module or pump motor, blown fuse or low voltage to the ABS module, damaged sensor wiring or corroded connector.
C1140 — Hydraulic Base Brake Failure (C1140): a chassis (brakes/steering/suspension) fault affecting the ABS / stability control. Short, gentle driving to a shop is usually possible. Most often caused by failed wheel speed sensor, blown fuse or low voltage to the ABS module, damaged sensor wiring or corroded connector.
C1141 — C1141 — Wheel Speed Sensor LF Tone Ring Tooth Missing Fault. A fault in the ABS / stability control. Short, gentle driving to a shop is usually possible. Typical causes: damaged sensor wiring or corroded connector, faulty ABS module or pump motor, damaged tone (reluctor) ring on the hub.
C1142 — Wheel Speed Sensor RF Tone Ring Tooth Missing Fault (C1142): a chassis (brakes/steering/suspension) fault affecting the ABS / stability control. Short, gentle driving to a shop is usually possible. Most often caused by damaged tone (reluctor) ring on the hub, failed wheel speed sensor, faulty ABS module or pump motor.
C1143 — C1143 — Wheel Speed Sensor LR Tone Ring Tooth Missing Fault. 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, damaged sensor wiring or corroded connector, failed wheel speed sensor.
C1144 — C1144 — Wheel Speed Sensor RR Tone Ring Tooth Missing Fault. A fault in the ABS / stability control. Short, gentle driving to a shop is usually possible. Typical causes: blown fuse or low voltage to the ABS module, damaged sensor wiring or corroded connector, faulty ABS module or pump motor.
C1145 — C1145 — Speed Wheel Sensor RF Input Circuit Failure. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: control module driver fault, faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit.