U0031
Vehicle Communication Bus A (+) Low
U0031 is an OBD-II diagnostic trouble code meaning: Vehicle Communication Bus A (+) Low. Common causes: open or short circuit in the can bus, oxidation of contacts in connectors. Estimated repair cost: $6–56.
Symptoms
- Incorrect operation of the dashboard
- Errors in the operation of various vehicle systems
- Periodic shutdown of electronic systems
- The Check Engine light comes on
- Problems starting the engine
Causes
- Open or short circuit in the CAN bus
- Oxidation of contacts in connectors
- Malfunction of one of the ECUs
- Problems with CAN bus power supply
- Mechanical damage to wiring
How to Fix
- Visual inspection of CAN bus wiring
- Checking contacts in connectors
- Measuring resistance and voltage on the CAN bus
- Disabling modules one by one to identify the faulty one
- Replacing damaged wires or connectors
Related codes
Error U0031 by Vehicle Brand
FAQ
What does the U0031 code mean?
U0031 is an OBD-II diagnostic trouble code that indicates: Vehicle Communication Bus A (+) Low
What causes a U0031 error code?
The most common causes of U0031 include: Open or short circuit in the CAN bus; Oxidation of contacts in connectors; Malfunction of one of the ECUs; Problems with CAN bus power supply.
How do I fix a U0031 diagnostic trouble code?
To fix U0031: Visual inspection of CAN bus wiring. Checking contacts in connectors. Measuring resistance and voltage on the CAN bus. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with U0031?
Limited driving only, diagnose soon
How much does it cost to fix U0031?
The estimated repair cost for U0031 is $6–56. Actual cost depends on your vehicle, location, and labor rates.
See also: Russian version · NationStat