OBD Codes List

Diagnostic reference · U0057

U0057

Vehicle Communication Bus D (+) Open

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

What it means

U0057 means Vehicle Communication Bus D (+) Open.

Check these first

  • An open in the bus D (+) wire between two modules
  • A broken or backed out pin at a bus D (+) connector
  • A module connector not fully seated on the bus D (+) circuit
  • Corrosion eating through the bus D (+) conductor

What to do next

  1. Read stored codes on every module that shares bus D
  2. Trace the bus D (+) wire end to end for an open
  3. Check each bus D (+) connector pin for a poor fit or backing out
  4. Repair or replace the open section of the bus D (+) wire
  5. Replace the module that stays off the bus D (+) line
  6. Clear the code and retest

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Updated

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