Skip to main content
Diagnose/U0100
U0100Critical SeverityElectrical

Lost Communication with ECM/PCM

What This Means

Another module on the vehicle has lost communication with the engine control module over the CAN bus network. This could indicate a wiring issue, a failed module, or a network problem.

Common Symptoms

  • Multiple warning lights
  • Engine may not start
  • Various systems non-functional
  • No communication during diagnostics

Common Causes

  • Failed ECM/PCM
  • CAN bus wiring damage
  • Corroded network connector
  • Power supply issue to ECM
  • Water damage

Estimated Repair Cost

$200 – $2000
Parts and labor (varies by vehicle and location)
Difficulty:Professional

Need This Fixed?

Find certified mechanics near you who can diagnose and repair U0100.

Find a Shop Near You
Search Another Code

For informational purposes only. Diagnostic trouble codes are starting points for diagnosis, not definitive answers. Always consult a certified mechanic for proper diagnosis and repair. Estimated costs vary by vehicle, location, and shop rates.