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

• C100D — OBD2 code C100D flags a problem with the ABS / stability control (C100D — brake pedal angle sensor circuit 1: causes, symptoms & fix). Short, gentle driving to a shop is usually possible. Common culprits: damaged sensor wiring or corroded connector, blown fuse or low voltage to the ABS module, faulty ABS module or pump motor.
• C100E — C100E — Brake Pedal Angle Sensor Circuit 2: Causes, Symptoms & Fix (C100E): a vehicle fault affecting the ABS / stability control. Short, gentle driving to a shop is usually possible. Most often caused by blown fuse or low voltage to the ABS module, damaged sensor wiring or corroded connector, failed wheel speed sensor.
• C100F — OBD2 code C100F flags a problem with the ABS / stability control (C100F — brake pedal angle sensor supply: causes, symptoms & fix). Short, gentle driving to a shop is usually possible. Common culprits: faulty ABS module or pump motor, damaged sensor wiring or corroded connector, damaged tone (reluctor) ring on the hub.
• C1010 — OBD2 code C1010 flags a problem with the sensor and actuator circuits (C1010 — continuous vacuum hublock (CVH) solenoid: causes, symptoms & fix). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit, control module driver fault.
• C1011 — C1011 — Brake Pedal Feel Simulator Cut-off Pressure Sensor: Causes, Symptoms & Fix (C1011): a vehicle fault affecting the ABS / stability control. Short, gentle driving to a shop is usually possible. Most often caused by damaged sensor wiring or corroded connector, blown fuse or low voltage to the ABS module, faulty ABS module or pump motor.
• C1012 — OBD2 code C1012 flags a problem with the ABS / stability control (C1012 — brake pedal feel simulator cut-off valve solenoid: causes, symptoms & fix). Short, gentle driving to a shop is usually possible. Common culprits: failed wheel speed sensor, damaged sensor wiring or corroded connector, damaged tone (reluctor) ring on the hub.
• C1013 — C1013 — C1013 — Brake System Pressure: Causes, Symptoms & Fix. 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, damaged tone (reluctor) ring on the hub.
• C1014 — C1014 — C1014 — Brake System Total Volume Balance: Causes, Symptoms & Fix. A fault in the ABS / stability control. Short, gentle driving to a shop is usually possible. Typical causes: failed wheel speed sensor, faulty ABS module or pump motor, blown fuse or low voltage to the ABS module.
• C1015 — C1015 — Vacuum Supply: Causes, Symptoms & Fix (C1015): a vehicle 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, poor ground connection, faulty sensor or actuator of the affected circuit.
• C1016 — OBD2 code C1016 flags a problem with the sensor and actuator circuits (C1016 — pedal angle to pedal feel simulator cut-off pressure comparison: causes, symptoms & fix). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, control module driver fault, poor ground connection.
• C1017 — C1017 — C1017 — Boot/Trunk Primary Switch: Causes, Symptoms & Fix. 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, faulty sensor or actuator of the affected circuit, control module driver fault.
• C1018 — C1018 — C1018 — Regenerative Braking: Causes, Symptoms & Fix. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: control module driver fault, corroded, loose or damaged connector, poor ground connection.
• C101A — C101A — C101A — Vacuum Pressure Sensor: Causes, Symptoms & Fix. 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, blown fuse feeding the circuit.
• C101B — OBD2 code C101B flags a problem with the sensor and actuator circuits (C101B — vacuum pressure sensor circuit B: causes, symptoms & fix). 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.
• C101C — OBD2 code C101C flags a problem with the ABS / stability control (C101C — brake vacuum pump: causes, symptoms & fix). Short, gentle driving to a shop is usually possible. Common culprits: damaged tone (reluctor) ring on the hub, faulty ABS module or pump motor, failed wheel speed sensor.
• C101D — C101D — C101D — Left Front Vertical Acceleration Sensor: Causes, Symptoms & Fix. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: control module driver fault, open or shorted wiring in the circuit, corroded, loose or damaged connector.
• C101E — C101E — Right Front Vertical Acceleration Sensor: Causes, Symptoms & Fix (C101E): a vehicle fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by blown fuse feeding the circuit, corroded, loose or damaged connector, poor ground connection.
• C101F — C101F — Generic Valve Failure: Causes, Symptoms & Fix (C101F): a vehicle fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by control module driver fault, blown fuse feeding the circuit, corroded, loose or damaged connector.
• C1020 — OBD2 code C1020 flags a problem with the ABS / stability control (C1020 — brake system fill not complete: causes, symptoms & fix). Short, gentle driving to a shop is usually possible. Common culprits: faulty ABS module or pump motor, damaged sensor wiring or corroded connector, blown fuse or low voltage to the ABS module.
• C1021 — OBD2 code C1021 flags a problem with the turbocharger / supercharger boost control (C1021 — ABS booster control pressure: causes, symptoms & fix). Short, gentle driving to a shop is usually possible. Common culprits: stuck wastegate or faulty boost control solenoid, clogged intake or exhaust (DPF/cat), boost leak in intercooler piping or hoses.
• C1022 — C1022 — C1022 — Boot/Trunk Secondary Switch: Causes, Symptoms & Fix. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: faulty sensor or actuator of the affected circuit, corroded, loose or damaged connector, open or shorted wiring in the circuit.
• C1025 — OBD2 code C1025 flags a problem with the turbocharger / supercharger boost control (C1025 — brake primary circuit overboost pressure: causes, symptoms & fix). Short, gentle driving to a shop is usually possible. Common culprits: stuck wastegate or faulty boost control solenoid, vacuum or actuator line damage, boost leak in intercooler piping or hoses.
• C1026 — C1026 — C1026 — ABS Secondary Circuit Overboost Pressure: Causes, Symptoms & Fix. A fault in the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Typical causes: boost leak in intercooler piping or hoses, faulty boost pressure sensor, stuck wastegate or faulty boost control solenoid.
• C1027 — OBD2 code C1027 flags a problem with the sensor and actuator circuits (C1027 — master cylinder to primary circuit pressure: causes, symptoms & fix). The car is usually drivable while you plan the repair. Common culprits: corroded, loose or damaged connector, open or shorted wiring in the circuit, blown fuse feeding the circuit.