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

• P1638 — P1638 — KAM Voltage Too Low. 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, poor ground connection, control module driver fault.
• P1639 — P1639 — Data Output Link Circuit Failure. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: poor ground connection, open or shorted wiring in the circuit, control module driver fault.
• P1640 — P1640 — Tire / Axle Ratio Out of Acceptable Range. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: poor ground connection, open or shorted wiring in the circuit, corroded, loose or damaged connector.
• P1641 — Inductive Signature Chip Communication Error (P1641): 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, open or shorted wiring in the circuit.
• P1642 — OBD2 code P1642 flags a problem with the vehicle network (CAN bus) communication (can link ECM/ABSCM circuit / network malfunction). Short, gentle driving to a shop is usually possible. Common culprits: a faulty module pulling the bus down, poor grounds or low battery voltage, corroded connectors, especially in wet areas.
• P1643 — OBD2 code P1643 flags a problem with the vehicle network (CAN bus) communication (can link ECM/INSTM circuit / network malfunction). Short, gentle driving to a shop is usually possible. Common culprits: water ingress in harness junctions, damaged CAN bus wiring or short to power/ground, poor grounds or low battery voltage.
• P1644 — OBD2 code P1644 flags a problem with the sensor and actuator circuits (vehicle ID block corrupted or not programmed). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit.
• P1645 — OBD2 code P1645 flags a problem with the sensor and actuator circuits (powertrain dtcs available in another module). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, control module driver fault, corroded, loose or damaged connector.
• P1646 — P1646 — Bank 1 Linear O2 Control Fault. P1646 usually affects fuel control, emissions, or drivability rather than immediate vehicle safety.
• P1647 — P1647 — Ford-Jaguar bank 2 O2 control-chip fault. P1647 is usually drivable if the engine runs smoothly and there are no emissions-related concerns.
• P1648 — P1648 — Jaguar Knock Sensor Input Circuit Fault. P1648 does not always prevent normal driving, but actual engine knock or detonation can damage internal engine components.
• P1649 — P1649 — ABS CAN Communication Failure. P1649 means the ABS module is not communicating on the CAN network, so anti-lock assistance may be unavailable even though basic hydraulic braking can remain functional.
• P1650 — Fuel Pump Primary Circuit Failure (P1650): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by vacuum or intake leaks skewing the mixture, faulty fuel pressure regulator, contaminated or incorrect fuel.
• P1651 — OBD2 code P1651 flags a problem with the fuel delivery and mixture control (fuel pump monitor circuit high input). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, weak fuel pump or clogged fuel filter, vacuum or intake leaks skewing the mixture.
• P1652 — Fuel Pump Monitor Circuit Low Input (P1652): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by contaminated or incorrect fuel, faulty fuel pressure regulator, clogged or leaking fuel injectors.
• P1653 — OBD2 code P1653 flags a problem with the fuel delivery and mixture control (fuel pump speed control circuit malfunction). Short, gentle driving to a shop is usually possible. Common culprits: contaminated or incorrect fuel, clogged or leaking fuel injectors, faulty fuel pressure regulator.
• P1654 — OBD2 code P1654 flags a problem with the fuel delivery and mixture control (fuel pump resistor switch circuit malfunction). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, contaminated or incorrect fuel, vacuum or intake leaks skewing the mixture.
• P1655 — OBD2 code P1655 flags a problem with the sensor and actuator circuits (PSP switch out of self test range). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, blown fuse feeding the circuit, control module driver fault.
• P1656 — P1656 — PCM CAN Network Communication Fault. If the engine runs normally and no network-related symptoms are present, drive cautiously to a repair shop.
• P1657 — P1657 — CAN Link Chip Malfunction. P1657 can compromise communication between vehicle modules.
• P1658 — P1658 — Fuel Injection Pump Supply Voltage Fault. The vehicle may continue operating, but rough running, hesitation, stalling, or a no-start condition is possible.
• P1659 — P1659 — Fuel Injection Pump Electrical Circuit Failure. P1659 can affect fuel delivery and cause stalling or a no-start condition.
• P1660 — OBD2 code P1660 flags a problem with the sensor and actuator circuits (PSP switch input malfunction). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, control module driver fault, blown fuse feeding the circuit.
• P1662 — OBD2 code P1662 flags a problem with the sensor and actuator circuits (power steering output circuit malfunction). The car is usually drivable while you plan the repair. Common culprits: open or shorted wiring in the circuit, poor ground connection, corroded, loose or damaged connector.