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.

U1900 — CAN Communication Bus Fault (U1900): 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, damaged CAN bus wiring or short to power/ground, corroded connectors, especially in wet areas.
U1950 — U1950 — UPB Communication Bus Fault. 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.
U2001 — OBD2 code U2001 flags a problem with the vehicle network (CAN bus) communication (audio tape deck unit is not responding). 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.
U2002 — Audio Bezel is Not Responding (U2002): 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, damaged CAN bus wiring or short to power/ground, a faulty module pulling the bus down.
U2003 — U2003 — Audio Compact Disk / Disk Jockey Unit is Not Responding. 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, water ingress in harness junctions.
U2004 — OBD2 code U2004 flags a problem with the vehicle network (CAN bus) communication (audio steering wheel control unit is not responding). Short, gentle driving to a shop is usually possible. Common culprits: poor grounds or low battery voltage, corroded connectors, especially in wet areas, damaged CAN bus wiring or short to power/ground.
U2005 — Audio Rear Integrated Control Panel Unit is Not Responding (U2005): 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, water ingress in harness junctions, corroded connectors, especially in wet areas.
U2006 — OBD2 code U2006 flags a problem with the vehicle network (CAN bus) communication (audio remote climate control unit is not responding). Short, gentle driving to a shop is usually possible. Common culprits: water ingress in harness junctions, corroded connectors, especially in wet areas, a faulty module pulling the bus down.
U2007 — Audio Navigation Unit is Not Responding (U2007): 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, aftermarket equipment interfering with the bus.
U2008 — Audio Phone is Not Responding (U2008): 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, poor grounds or low battery voltage, corroded connectors, especially in wet areas.
U2009 — Audio Front Control Module (ACM) is Not Responding (U2009): 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, water ingress in harness junctions, poor grounds or low battery voltage.
U2010 — OBD2 code U2010 flags a problem with the vehicle network (CAN bus) communication (module is not responding (non SCP)). Short, gentle driving to a shop is usually possible. Common culprits: aftermarket equipment interfering with the bus, poor grounds or low battery voltage, corroded connectors, especially in wet areas.
U2011 — Module Transmitted Invalid Data (Non SCP) (U2011): 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, a faulty module pulling the bus down.
U2012 — Communication Bus Error (Non SCP) (U2012): 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, water ingress in harness junctions, damaged CAN bus wiring or short to power/ground.
U2013 — U2013 — Compass Module is not Responding. 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, aftermarket equipment interfering with the bus, water ingress in harness junctions.
U2014 — OBD2 code U2014 flags a problem with the vehicle network (CAN bus) communication (audio subwoofer unit is not responding). 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, water ingress in harness junctions.
U2015 — Signal Link Fault (Non SCP) (U2015): 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, damaged CAN bus wiring or short to power/ground.
U2016 — OBD2 code U2016 flags a problem with the vehicle network (CAN bus) communication (signal link short to ground (non SCP) / from NGV module). Short, gentle driving to a shop is usually possible. Common culprits: water ingress in harness junctions, poor grounds or low battery voltage, aftermarket equipment interfering with the bus.
U2017 — U2017 — Driver Side Crash Sensor Communication Fault (Non SCP). A fault in the airbag / restraint system (SRS). Short, gentle driving to a shop is usually possible. Typical causes: damaged wiring under seats or in the steering column, SRS control module fault or stored crash data, failed clockspring (driver airbag circuit).
U2018 — U2018 — Passenger Side Crash Sensor Communication Fault (Non SCP). A fault in the airbag / restraint system (SRS). Short, gentle driving to a shop is usually possible. Typical causes: faulty impact or occupancy sensor, damaged wiring under seats or in the steering column, depleted backup battery or low system voltage.
U2019 — Audio Voice Module Not Responding (U2019): 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, water ingress in harness junctions.
U2020 — OBD2 code U2020 flags a problem with the vehicle network (CAN bus) communication (audio center amp is not responding). 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, corroded connectors, especially in wet areas.
U2021 — U2021 — Invalid /fault data received (Non SCP). 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, poor grounds or low battery voltage, aftermarket equipment interfering with the bus.
U2022 — U2022 — Dedicated Communication Protocol Fault. U2022 can sometimes be stored without an obvious driving symptom, but it identifies a fault in a control-module communication path.