Network
generic / SAE
U0189
Lost Communication with Auxiliary Heater Control Module
The HVAC controller has lost the auxiliary fuel-fired heater module. Pre-heating cannot be commanded; the heater stays inactive.
SystemNetwork
Typegeneric / SAE
GroupU0
Range / number1 / 89
Possible causes
- Auxiliary heater unpowered high
- Gateway module routing CAN messages incorrectly low
- CAN terminating resistor (120 Ω) drifted out of spec low
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 80–700 €
- Estimated time: 0.5–3 h
- Component: auxiliary heater
- Component: can bus wiring
Sources
References
sae:J2012