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U0100Lost communication with ECM/PCM

Universal diagnostic code. Below: what it means, common causes, symptoms, and the exact bench-programming fix path.

Common causes

  • ECM power lost
  • ECM internal failure
  • CAN-bus break to ECM

Symptoms you'll see

  • No ECM data
  • Cluster shows engine warnings
  • Crank-no-start

The fix path

Verify ECM power + ground first. If ECM is genuinely failed, brand-specific bench services apply.

AML services that fix this

Mail in the affected module, we bench-program, ship back next business day. Flat pricing, return shipping included.

Related diagnostic codes

Not sure which service applies?

Text us your year/make/model + which scanner caught the code — we'll tell you exactly which module to ship and which service to pick.