OBD Codes List

Diagnostic reference · U0005

U0005

High Speed CAN Communication Bus (+) High

System
Network communication (U code)
Lamp
Check Engine Light
Category
Network Communications

What it means

U0005 means High Speed CAN Communication Bus (+) High.

Check these first

  • A short to voltage on the high speed CAN positive wire
  • A failed transceiver holding the high speed CAN positive line high
  • Harness damage shorting the high speed CAN positive wire to power
  • A faulty module on the high speed CAN network

What to do next

  1. Read the code and check module communication status on a scan tool
  2. Measure high speed CAN positive voltage with the key on
  3. Test the high speed CAN positive wire for a short to voltage
  4. Unplug modules one at a time to see if the line returns to normal
  5. Replace the module that holds the high speed CAN positive line high
  6. Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.