What does code U0106 mean?
Symptoms seen in the workshop
- Glow plug light flashing or MIL on
- Hard cold starts, white smoke on start-up
- DPF regeneration restricted on some models
Common causes of code U0106
- Faulty glow plug module (heat and vibration in the engine bay)
- No power supply: high-current fuse or ground
- Replacement module with a different part number or without communication
- Corroded connector or damaged wiring
Fix by ECU remapping
First, check the module and glow plugs: if they do not heat up, cold starting depends on them and they must be repaired.
DTC OFF: deactivation of U0106 and associated codes (P0670 and glow plug circuit codes) only when the module works but does not communicate (for example, a replacement module without communication that does switch the glow plugs), or on conversions where pre-heating is managed differently.
Disabling the warning with a faulty system does not improve cold starting and can hide a failed glow plug.
⚠️ Important: Disabling the DTC without the correct calibration of the related system (DTC OFF) is not a valid fix. Both the calibration maps and the diagnostic mask have to be modified.
