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

• U1219 — OBD2 code U1219 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for external lamps). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, water ingress in harness junctions, a faulty module pulling the bus down.
• U1220 — SCP (J1850) Invalid or Missing Data for Interior Lamp Outage (U1220): 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, poor grounds or low battery voltage, damaged CAN bus wiring or short to power/ground.
• U1221 — SCP (J1850) Invalid or Missing Data for Interior Lamp Outage (U1221): 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, damaged CAN bus wiring or short to power/ground, corroded connectors, especially in wet areas.
• U1222 — U1222 — SCP (J1850) Invalid or Missing Data for Interior Lamps. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: water ingress in harness junctions, aftermarket equipment interfering with the bus, a faulty module pulling the bus down.
• U1223 — U1223 — SCP (J1850) Invalid or Missing Data for Interior Lamps. 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, poor grounds or low battery voltage, corroded connectors, especially in wet areas.
• U1224 — SCP (J1850) Invalid or Missing Data for Primary Id (U1224): 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, poor grounds or low battery voltage, corroded connectors, especially in wet areas.
• U1225 — OBD2 code U1225 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: damaged CAN bus wiring or short to power/ground, water ingress in harness junctions, corroded connectors, especially in wet areas.
• U1226 — SCP (J1850) Invalid or Missing Data for Body Status Request (U1226): 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, damaged CAN bus wiring or short to power/ground.
• U1227 — SCP (J1850) Invalid or Missing Data for Body Status Request (U1227): 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, aftermarket equipment interfering with the bus, water ingress in harness junctions.
• U1228 — U1228 — SCP (J1850) Invalid or Missing Data for Tires. 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, poor grounds or low battery voltage, water ingress in harness junctions.
• U1229 — U1229 — SCP (J1850) Invalid or Missing Data for Tires. 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.
• U1230 — U1230 — SCP (J1850) Invalid or Missing Data for Electric Defrost. 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, damaged CAN bus wiring or short to power/ground.
• U1231 — SCP (J1850) Invalid or Missing Data for Electric Defrost (U1231): 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, aftermarket equipment interfering with the bus, poor grounds or low battery voltage.
• U1232 — OBD2 code U1232 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for navigation). Short, gentle driving to a shop is usually possible. Common culprits: damaged CAN bus wiring or short to power/ground, a faulty module pulling the bus down, corroded connectors, especially in wet areas.
• U1233 — SCP (J1850) Invalid or Missing Data for Navigation (U1233): 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, a faulty module pulling the bus down, aftermarket equipment interfering with the bus.
• U1234 — SCP (J1850) Invalid or Missing Data for Displays (U1234): 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, water ingress in harness junctions, aftermarket equipment interfering with the bus.
• U1236 — OBD2 code U1236 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for memory storage). 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.
• U1237 — U1237 — SCP (J1850) Invalid or Missing Data for Memory Storage. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: aftermarket equipment interfering with the bus, poor grounds or low battery voltage, damaged CAN bus wiring or short to power/ground.
• U1238 — OBD2 code U1238 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for experimental #4). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, water ingress in harness junctions, poor grounds or low battery voltage.
• U1239 — SCP (J1850) Invalid or Missing Data for Experimental #4 (U1239): 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, a faulty module pulling the bus down, water ingress in harness junctions.
• U1240 — OBD2 code U1240 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: water ingress in harness junctions, damaged CAN bus wiring or short to power/ground, poor grounds or low battery voltage.
• U1241 — OBD2 code U1241 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: corroded connectors, especially in wet areas, poor grounds or low battery voltage, a faulty module pulling the bus down.
• U1242 — OBD2 code U1242 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for exterior environment). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, a faulty module pulling the bus down, water ingress in harness junctions.
• U1243 — OBD2 code U1243 flags a problem with the vehicle network (CAN bus) communication (SCP (J1850) invalid or missing data for exterior environment). Short, gentle driving to a shop is usually possible. Common culprits: a faulty module pulling the bus down, damaged CAN bus wiring or short to power/ground, poor grounds or low battery voltage.