U0100
Lost Communication with ECM/PCM "A"
System: Network
Severity: medium
What does U0100 mean?
The DTC U0100 (Lost Communication with ECM/PCM "A") is a fault code stored by the ECU when it detects a lost comm ECM condition in the network subsystem. It is commonly seen on European and Asian vehicles using Bosch, Continental, Siemens or Denso ECUs.
Common causes of U0100
- Failed ECM
- CAN bus wiring fault
- Bad ECM power/ground
- Terminating resistor failure
How to fix U0100
Check ECM power + ground. CAN bus diagnostic with scope (60Ω between CAN-H/L when powered).
Tuning approach with DaVinci Deluxe
For U0100, DaVinci Deluxe offers the following ECU map adjustments and software solutions:
- (network repair required)
- ECU flash recovery if ECM is alive but unreachable
Need to fix U0100 on your ECU?
DaVinci Deluxe is professional ECU tuning software trusted by 800+ workshops. Lifetime license €299, 10 minutes free trial.
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