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

• U0490 — U0490 — U0490 - Invalid Data Received From Active Safety Control Module 53. 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, water ingress in harness junctions.
• U0491 — Invalid Data Received From Digital Disc Player/Changer Module "D" (U0491): 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, damaged CAN bus wiring or short to power/ground.
• U0492 — U0492 — Invalid Data Received From Television. 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, a faulty module pulling the bus down, aftermarket equipment interfering with the bus.
• U0493 — Invalid Data Received From Personal Computer (U0493): 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.
• U0494 — Invalid Data Received From "Digital Audio Control Module A" (U0494): 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, aftermarket equipment interfering with the bus.
• U0495 — OBD2 code U0495 flags a problem with the vehicle network (CAN bus) communication (invalid data received from "digital audio control module B"). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, aftermarket equipment interfering with the bus, water ingress in harness junctions.
• U0496 — U0496 — Invalid Data Received From Subscription Entertainment Receiver Module. 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, damaged CAN bus wiring or short to power/ground, poor grounds or low battery voltage.
• U0497 — U0497 — Invalid Data Received From Entertainment Control Module Rear "A". 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, damaged CAN bus wiring or short to power/ground, water ingress in harness junctions.
• U0498 — OBD2 code U0498 flags a problem with the vehicle network (CAN bus) communication (invalid data received from telephone control module). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, damaged CAN bus wiring or short to power/ground, poor grounds or low battery voltage.
• U0499 — Invalid Data Received From Telematic Control Module (U0499): 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, corroded connectors, especially in wet areas, poor grounds or low battery voltage.
• U049A — OBD2 code U049A flags a problem with the vehicle network (CAN bus) communication (invalid data received from "door control module A"). Short, gentle driving to a shop is usually possible. Common culprits: aftermarket equipment interfering with the bus, water ingress in harness junctions, damaged CAN bus wiring or short to power/ground.
• U0500 — U0500 — U0500 - Invalid Data Received From Active Safety Control Module 63. 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, a faulty module pulling the bus down.
• U0502 — OBD2 code U0502 flags a problem with the vehicle network (CAN bus) communication (invalid data received from "door control module C"). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, water ingress in harness junctions, aftermarket equipment interfering with the bus.
• U0503 — Invalid Data Received From "Door Control Module D" (U0503): 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.
• U0504 — Invalid Data Received From "Door Control Module E" (U0504): 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, water ingress in harness junctions, aftermarket equipment interfering with the bus.
• U0505 — OBD2 code U0505 flags a problem with the vehicle network (CAN bus) communication (invalid data received from "door control module F"). Short, gentle driving to a shop is usually possible. Common culprits: corroded connectors, especially in wet areas, damaged CAN bus wiring or short to power/ground, aftermarket equipment interfering with the bus.
• U0506 — U0506 — Invalid Data Received From "Door Control Module G". 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.
• U0507 — OBD2 code U0507 flags a problem with the vehicle network (CAN bus) communication (invalid data received from folding top control module). Short, gentle driving to a shop is usually possible. Common culprits: a faulty module pulling the bus down, corroded connectors, especially in wet areas, water ingress in harness junctions.
• U0508 — U0508 — Invalid Data Received From Moveable Roof Control Module. 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, aftermarket equipment interfering with the bus.
• U0509 — Invalid Data Received From "Seat Control Module A" (U0509): 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, a faulty module pulling the bus down, damaged CAN bus wiring or short to power/ground.
• U050A — Invalid Data Received From "Seat Control Module B" (U050A): 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, corroded connectors, especially in wet areas, poor grounds or low battery voltage.
• U0510 — U0510 — U0510 - Invalid Data Received From Active Safety Control Module 73. 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, poor grounds or low battery voltage, a faulty module pulling the bus down.
• U0511 — OBD2 code U0511 flags a problem with the vehicle network (CAN bus) communication (invalid data received from "seat control module C"). Short, gentle driving to a shop is usually possible. Common culprits: aftermarket equipment interfering with the bus, corroded connectors, especially in wet areas, poor grounds or low battery voltage.
• U0512 — U0512 — Invalid Data Received From "Seat Control Module D". 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, aftermarket equipment interfering with the bus, poor grounds or low battery voltage.