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.

U1244 — U1244 — SCP (J1850) Invalid or Missing Data for Interior Environment. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: a faulty module pulling the bus down, damaged CAN bus wiring or short to power/ground, aftermarket equipment interfering with the bus.
U1245 — OBD2 code U1245 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for interior environment). Short, gentle driving to a shop is usually possible. Common culprits: water ingress in harness junctions, corroded connectors, especially in wet areas, aftermarket equipment interfering with the bus.
U1246 — U1246 — SCP (J1850) Invalid or Missing Data for Primary Id. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: damaged CAN bus wiring or short to power/ground, corroded connectors, especially in wet areas, water ingress in harness junctions.
U1247 — OBD2 code U1247 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for primary id). Short, gentle driving to a shop is usually possible. Common culprits: poor grounds or low battery voltage, aftermarket equipment interfering with the bus, a faulty module pulling the bus down.
U1248 — U1248 — SCP (J1850) Invalid or Missing Data for Time / Date. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: corroded connectors, especially in wet areas, a faulty module pulling the bus down, water ingress in harness junctions.
U1249 — SCP (J1850) Invalid or Missing Data for Time / Date (U1249): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by poor grounds or low battery voltage, corroded connectors, especially in wet areas, water ingress in harness junctions.
U1250 — SCP (J1850) Invalid or Missing Data for Vehicle Id (VIN) (U1250): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by a faulty module pulling the bus down, aftermarket equipment interfering with the bus, poor grounds or low battery voltage.
U1251 — SCP (J1850) Invalid or Missing Data for Vehicle Id (VIN) (U1251): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by poor grounds or low battery voltage, aftermarket equipment interfering with the bus, corroded connectors, especially in wet areas.
U1252 — OBD2 code U1252 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for class a functions). Short, gentle driving to a shop is usually possible. Common culprits: damaged CAN bus wiring or short to power/ground, poor grounds or low battery voltage, a faulty module pulling the bus down.
U1253 — U1253 — SCP (J1850) Invalid or Missing Data for Class A Functions. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: damaged CAN bus wiring or short to power/ground, aftermarket equipment interfering with the bus, poor grounds or low battery voltage.
U1254 — U1254 — SCP (J1850) Invalid or Missing Data for Network Control. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: poor grounds or low battery voltage, a faulty module pulling the bus down, damaged CAN bus wiring or short to power/ground.
U1255 — SCP (J1850) Invalid or Missing Data for Network Control (U1255): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by corroded connectors, especially in wet areas, a faulty module pulling the bus down, damaged CAN bus wiring or short to power/ground.
U1260 — OBD2 code U1260 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) single ended (+) circuit failure). Short, gentle driving to a shop is usually possible. Common culprits: a faulty module pulling the bus down, water ingress in harness junctions, corroded connectors, especially in wet areas.
U1261 — SCP (J1850) Single Ended (-) Circuit Failure (U1261): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by aftermarket equipment interfering with the bus, damaged CAN bus wiring or short to power/ground, poor grounds or low battery voltage.
U1308 — SCP (J1850) Invalid or Missing Data for Function Read Engine Torque (U1308): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by water ingress in harness junctions, aftermarket equipment interfering with the bus, poor grounds or low battery voltage.
U1341 — SCP (J1850) Invalid or Missing Data for Function Read Vehicle Speed (U1341): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by water ingress in harness junctions, aftermarket equipment interfering with the bus, damaged CAN bus wiring or short to power/ground.
U1430 — SCP (J1850) Invalid or Missing Data for Function Read Fuel System (U1430): a vehicle network fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by weak fuel pump or clogged fuel filter, contaminated or incorrect fuel, faulty fuel pressure regulator.
U1451 — SCP (J1850) Invalid or Missing Data for Function Read Audible Warnings /Anti-Theft Module (U1451): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by poor grounds or low battery voltage, aftermarket equipment interfering with the bus, a faulty module pulling the bus down.
U1612 — SCP (J1850) Lack of Acknowledgment for Primary Id (U1612): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by a faulty module pulling the bus down, corroded connectors, especially in wet areas, damaged CAN bus wiring or short to power/ground.
U1736 — U1736 — SCP (J1850) Lack of Acknowledgment for Telltales. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: poor grounds or low battery voltage, a faulty module pulling the bus down, corroded connectors, especially in wet areas.
U1794 — SCP (J1850) Lack of Acknowledgment for Mirrors (U1794): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by corroded connectors, especially in wet areas, a faulty module pulling the bus down, damaged CAN bus wiring or short to power/ground.
U1797 — U1797 — SCP (J1850) Lack of Acknowledgment for Door Locks. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: poor grounds or low battery voltage, corroded connectors, especially in wet areas, aftermarket equipment interfering with the bus.
U1798 — SCP (J1850) Lack of Acknowledgment for External Access (Doors) (U1798): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by damaged CAN bus wiring or short to power/ground, a faulty module pulling the bus down, aftermarket equipment interfering with the bus.
U1806 — OBD2 code U1806 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) lack of acknowledgment for primary id). Short, gentle driving to a shop is usually possible. Common culprits: poor grounds or low battery voltage, a faulty module pulling the bus down, water ingress in harness junctions.