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

• P1604 — P1604 — TCU Unable To Control Desired Throttle Angle. A fault in the throttle and intake air metering. Short, gentle driving to a shop is usually possible. Typical causes: intake air leaks after the MAF sensor, failed electronic throttle motor, contaminated or failed MAF/MAP sensor.
• P1605 — Loss of KAM Power; Open Circuit (P1605): a powertrain (engine/transmission) 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, open or shorted wiring in the circuit.
• P1606 — P1606 — ECM/TCM Serial Communication Error. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: poor ground connection, faulty sensor or actuator of the affected circuit, control module driver fault.
• P1607 — P1607 — Immobilizer/ECM Communication Error. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: open or shorted wiring in the circuit, corroded, loose or damaged connector, blown fuse feeding the circuit.
• P1609 — Code Word Unregestered (P1609): a powertrain (engine/transmission) 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, faulty sensor or actuator of the affected circuit, poor ground connection.
• P1612 — OBD2 code P1612 flags a problem with the sensor and actuator circuits (MIL O/P circuit malfunction). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, control module driver fault, faulty sensor or actuator of the affected circuit.
• P1613 — P1613 — Internal ECM Malfunction. 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.
• P1616 — OBD2 code P1616 flags a problem with the sensor and actuator circuits (SBDS interactive codes). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, corroded, loose or damaged connector, open or shorted wiring in the circuit.
• P1617 — SBDS Interactive Codes (P1617): a powertrain (engine/transmission) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by poor ground connection, open or shorted wiring in the circuit, blown fuse feeding the circuit.
• P1618 — OBD2 code P1618 flags a problem with the sensor and actuator circuits (SBDS interactive codes). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, corroded, loose or damaged connector, blown fuse feeding the circuit.
• P1619 — OBD2 code P1619 flags a problem with the sensor and actuator circuits (SBDS interactive codes). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, corroded, loose or damaged connector, blown fuse feeding the circuit.
• P1620 — SBDS Interactive Codes (P1620): a powertrain (engine/transmission) 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, control module driver fault, corroded, loose or damaged connector.
• P1621 — SBDS Interactive Codes (P1621): a powertrain (engine/transmission) 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, open or shorted wiring in the circuit, blown fuse feeding the circuit.
• P1622 — OBD2 code P1622 flags a problem with the sensor and actuator circuits (SBDS interactive codes). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, open or shorted wiring in the circuit, faulty sensor or actuator of the affected circuit.
• P1624 — SBDS Interactive Codes (P1624): a powertrain (engine/transmission) 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, corroded, loose or damaged connector.
• P1625 — SBDS Interactive Codes (P1625): a powertrain (engine/transmission) 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, open or shorted wiring in the circuit, blown fuse feeding the circuit.
• P1626 — OBD2 code P1626 flags a problem with the sensor and actuator circuits (control module long term memory performance/ immobilizer code words do not match). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, blown fuse feeding the circuit, control module driver fault.
• P1627 — Immobilizer ID Does Not Match (P1627): a powertrain (engine/transmission) 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, open or shorted wiring in the circuit, poor ground connection.
• P1628 — Immobilizer Code Word/ID Number Write Failure (P1628): a powertrain (engine/transmission) 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, faulty sensor or actuator of the affected circuit.
• P1630 — B+ Supply To VCRM Fan Circuit Malfunction (P1630): a powertrain (engine/transmission) 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, open or shorted wiring in the circuit, poor ground connection.
• P1633 — P1633 — Module Ignition Supply Input Malfunction. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: failed ignition coil or coil pack, faulty ignition control circuit in the ECM, moisture or oil in the spark plug wells.
• P1634 — OBD2 code P1634 flags a problem with the sensor and actuator circuits (internal voltage regulator malfunction). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, corroded, loose or damaged connector, open or shorted wiring in the circuit.
• P1635 — Internal Vref Malfunction (P1635): a powertrain (engine/transmission) 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, corroded, loose or damaged connector.
• P1637 — P1637 — Smart Alternator Faults Sensor/Circuit Malfunction. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: open or shorted wiring in the circuit, corroded, loose or damaged connector, poor ground connection.