OBD Codes List

Diagnostic reference · U008C

U008C

Vehicle Communication Bus G (+) Low

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

What it means

U008C means Vehicle Communication Bus G (+) Low.

Check these first

  • A short to ground on the bus G (+) wire
  • A module on bus G pulling the (+) line low
  • Water in a connector bridging the bus G (+) line to ground
  • A partially shorted accessory on the bus G (+) circuit

What to do next

  1. Read stored codes on every module that shares bus G
  2. Measure the bus G (+) line for an unwanted path to ground
  3. Check bus G (+) connectors for water or corrosion
  4. Disconnect added accessories to see if the bus G (+) line recovers
  5. Replace the module holding the bus G (+) line low
  6. Clear the code and retest

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Updated

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