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

• P1796 — TP (Electric) Circuit Malfunction (P1796): 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, corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit.
• P1797 — Barometer Pressure Circuit Malfunction (P1797): 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.
• P1798 — P1798 — Intake Air Volume Circuit Malfunction. A fault in the throttle and intake air metering. Short, gentle driving to a shop is usually possible. Typical causes: contaminated or failed MAF/MAP sensor, dirty throttle body or stuck throttle plate, faulty throttle position sensor or pedal sensor.
• P1799 — OBD2 code P1799 flags a problem with the sensor and actuator circuits (battery voltage circuit malfunction). The car is usually drivable while you plan the repair. Common culprits: control module driver fault, open or shorted wiring in the circuit, blown fuse feeding the circuit.
• P1801 — OBD2 code P1801 flags a problem with the sensor and actuator circuits (kick down switch circuit malfunction). 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.
• P1802 — P1802 — Neutral Switch Circuit Malfunction. 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, open or shorted wiring in the circuit.
• P1803 — OBD2 code P1803 flags a problem with the engine cooling and temperature control (coolant temperature circuit malfunction). Short, gentle driving to a shop is usually possible. Common culprits: faulty coolant temperature sensor, thermostat stuck open or closed, wiring faults in the sensor circuit.
• P1804 — Hold Switch Circuit Malfunction (P1804): 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 faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit, corroded, loose or damaged connector.
• P1805 — P1805 — Transmission Clutch Interlock Safety Switch Circuit Failure. A fault in the automatic transmission control. Short, gentle driving to a shop is usually possible. Typical causes: failed shift or pressure control solenoid, internal mechanical wear (clutches, torque converter), wiring or connector faults in the valve body harness.
• P1807 — P1807 — Transmission Clutch Interlock Safety Switch Short Circuit To Battery. A fault in the automatic transmission control. Short, gentle driving to a shop is usually possible. Typical causes: wiring or connector faults in the valve body harness, faulty transmission speed sensor, internal mechanical wear (clutches, torque converter).
• P1808 — Transmission Clutch Interlock Safety Switch Short Circuit To Ground (P1808): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by internal mechanical wear (clutches, torque converter), valve body wear, faulty transmission speed sensor.
• P1809 — Transmission 4-Wheel Drive High Indicator Circuit Failure (P1809): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by wiring or connector faults in the valve body harness, low or degraded transmission fluid, internal mechanical wear (clutches, torque converter).
• P1810 — Transmission 4-Wheel Drive High Indicator Open Circuit (P1810): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by faulty transmission speed sensor, wiring or connector faults in the valve body harness, internal mechanical wear (clutches, torque converter).
• P1811 — P1811 — Transmission 4-Wheel Drive High Indicator Short Circuit To Battery. A fault in the automatic transmission control. Short, gentle driving to a shop is usually possible. Typical causes: faulty transmission speed sensor, wiring or connector faults in the valve body harness, valve body wear.
• P1812 — OBD2 code P1812 flags a problem with the automatic transmission control (transmission 4-wheel drive high indicator short circuit to ground). Short, gentle driving to a shop is usually possible. Common culprits: faulty transmission speed sensor, valve body wear, internal mechanical wear (clutches, torque converter).
• P1813 — P1813 — Transmission 4-Wheel Drive Low Indicator Circuit Failure. A fault in the automatic transmission control. Short, gentle driving to a shop is usually possible. Typical causes: valve body wear, faulty transmission speed sensor, internal mechanical wear (clutches, torque converter).
• P1814 — OBD2 code P1814 flags a problem with the automatic transmission control (transmission 4-wheel drive low indicator open circuit). Short, gentle driving to a shop is usually possible. Common culprits: wiring or connector faults in the valve body harness, internal mechanical wear (clutches, torque converter), valve body wear.
• P1815 — OBD2 code P1815 flags a problem with the automatic transmission control (TFP valve position switch circuit/ transmission 4-wheel drive low indicator short circuit to battery). Short, gentle driving to a shop is usually possible. Common culprits: valve body wear, failed shift or pressure control solenoid, internal mechanical wear (clutches, torque converter).
• P1816 — Transmission 4-Wheel Drive Low Indicator Short Circuit To Ground (P1816): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by faulty transmission speed sensor, failed shift or pressure control solenoid, wiring or connector faults in the valve body harness.
• P1817 — OBD2 code P1817 flags a problem with the automatic transmission control (transmission 4-wheel drive mode select circuit failure). Short, gentle driving to a shop is usually possible. Common culprits: faulty transmission speed sensor, low or degraded transmission fluid, wiring or connector faults in the valve body harness.
• P1818 — OBD2 code P1818 flags a problem with the automatic transmission control (transmission 4-wheel drive mode select open circuit). Short, gentle driving to a shop is usually possible. Common culprits: internal mechanical wear (clutches, torque converter), failed shift or pressure control solenoid, faulty transmission speed sensor.
• P1819 — OBD2 code P1819 flags a problem with the automatic transmission control (transmission 4-wheel drive mode select short circuit to battery). Short, gentle driving to a shop is usually possible. Common culprits: faulty transmission speed sensor, valve body wear, failed shift or pressure control solenoid.
• P1820 — OBD2 code P1820 flags a problem with the automatic transmission control (transmission 4-wheel drive mode select short circuit to ground). Short, gentle driving to a shop is usually possible. Common culprits: failed shift or pressure control solenoid, valve body wear, internal mechanical wear (clutches, torque converter).
• P1821 — OBD2 code P1821 flags a problem with the automatic transmission control (transmission neutral safety switch circuit failure). Short, gentle driving to a shop is usually possible. Common culprits: faulty transmission speed sensor, internal mechanical wear (clutches, torque converter), wiring or connector faults in the valve body harness.