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

• P1822 — OBD2 code P1822 flags a problem with the automatic transmission control (transmission neutral safety switch open circuit). Short, gentle driving to a shop is usually possible. Common culprits: valve body wear, low or degraded transmission fluid, failed shift or pressure control solenoid.
• P1823 — Transmission Neutral Safety Switch Short Circuit To Battery (P1823): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by valve body wear, failed shift or pressure control solenoid, wiring or connector faults in the valve body harness.
• P1825 — P1825 — Transmission Transfer Case Clockwise Shift Relay Coil Circuit Failure. 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, valve body wear.
• P1826 — P1826 — Transmission Transfer Case Clockwise Shift Relay Coil Open Circuit. 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, low or degraded transmission fluid, faulty transmission speed sensor.
• P1827 — Transmission Transfer Case Clockwise Shift Relay Coil Short Circuit To Battery (P1827): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by low or degraded transmission fluid, wiring or connector faults in the valve body harness, valve body wear.
• P1828 — P1828 — Transmission Transfer Case Clockwise Shift Relay Coil Short Circuit To Ground. 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), valve body wear.
• P1829 — Transmission 4-Wheel Drive Clutch Relay Circuit Failure (P1829): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by valve body wear, failed shift or pressure control solenoid, low or degraded transmission fluid.
• P1831 — OBD2 code P1831 flags a problem with the automatic transmission control (transmission 4-wheel drive low clutch relay circuit to battery). Short, gentle driving to a shop is usually possible. Common culprits: valve body wear, wiring or connector faults in the valve body harness, faulty transmission speed sensor.
• P1832 — P1832 — Transmission 4-Wheel Drive Low Clutch Relay Circuit To Ground. A fault in the automatic transmission control. Short, gentle driving to a shop is usually possible. Typical causes: faulty transmission speed sensor, valve body wear, low or degraded transmission fluid.
• P1833 — P1833 — Transmission Transfer Case Counter Clockwise Shift Relay Coil Circuit Failure. A fault in the automatic transmission control. Short, gentle driving to a shop is usually possible. Typical causes: internal mechanical wear (clutches, torque converter), failed shift or pressure control solenoid, faulty transmission speed sensor.
• P1834 — OBD2 code P1834 flags a problem with the automatic transmission control (transmission transfer case counter clockwise shift relay coil open circuit). Short, gentle driving to a shop is usually possible. Common culprits: valve body wear, internal mechanical wear (clutches, torque converter), low or degraded transmission fluid.
• P1835 — Transmission Transfer Case Counter Clockwise Shift Relay Coil Short Circuit To Battery (P1835): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by failed shift or pressure control solenoid, low or degraded transmission fluid, valve body wear.
• P1836 — P1836 — Transmission Transfer Case Counter Clockwise Shift Relay Coil Short Circuit To Ground. 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, valve body wear, failed shift or pressure control solenoid.
• P1837 — OBD2 code P1837 flags a problem with the automatic transmission control (transmission transfer case differential lock-up solenoid circuit failure). Short, gentle driving to a shop is usually possible. Common culprits: valve body wear, low or degraded transmission fluid, faulty transmission speed sensor.
• P1838 — P1838 — Transmission Transfer Case Differential Lock-Up Solenoid Open Circuit. 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, failed shift or pressure control solenoid, low or degraded transmission fluid.
• P1839 — P1839 — Transmission Transfer Case Differential Lock-Up Solenoid 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, low or degraded transmission fluid, internal mechanical wear (clutches, torque converter).
• P1840 — Transmission Transfer Case Differential Lock-Up Solenoid Short Circuit To Ground (P1840): 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, faulty transmission speed sensor, failed shift or pressure control solenoid.
• P1841 — Transmission Transfer Case Front Shaft Speed Sensor Circuit Failure (P1841): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by low or degraded transmission fluid, failed shift or pressure control solenoid, internal mechanical wear (clutches, torque converter).
• P1842 — Transmission Transfer Case Rear Shaft Speed Sensor Circuit Failure (P1842): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by low or degraded transmission fluid, wiring or connector faults in the valve body harness, failed shift or pressure control solenoid.
• P1843 — OBD2 code P1843 flags a problem with the automatic transmission control (transmission transfer case shift motor circuit failure). Short, gentle driving to a shop is usually possible. Common culprits: internal mechanical wear (clutches, torque converter), valve body wear, wiring or connector faults in the valve body harness.
• P1844 — Transmission Transfer Case Shift Motor Open Circuit (P1844): 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), failed shift or pressure control solenoid, wiring or connector faults in the valve body harness.
• P1846 — Transmission Transfer Case Shift Motor Short Circuit To Ground (P1846): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by failed shift or pressure control solenoid, faulty transmission speed sensor, internal mechanical wear (clutches, torque converter).
• P1847 — OBD2 code P1847 flags a problem with the automatic transmission control (transmission transfer case differential lock-up feedback switch circuit failure). 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).
• P1850 — Transmission Transfer Case Differential Lock-Up Feedback Switch Short Circuit To Ground (P1850): a powertrain (engine/transmission) fault affecting the automatic transmission control. Short, gentle driving to a shop is usually possible. Most often caused by failed shift or pressure control solenoid, low or degraded transmission fluid, wiring or connector faults in the valve body harness.