What does code U0166 mean?

Q: What does code U0166 mean?

Lost Communication With Auxiliary Heater Control Module. U0166 means the vehicle's main network gateway or engine control module has stopped receiving regular status messages from the auxiliary heater control module over the controller area network (CAN) bus. The computer sets this code when the expected periodic signal from that module goes missing for a calibrated time, not when the heater itself fails electrically.

DTC codes / U01xx · Lost communication with a control module / U0166

U0166Lost Communication With Auxiliary Heater Control Module

U0166 means the vehicle's main network gateway or engine control module has stopped receiving regular status messages from the auxiliary heater control module over the controller area network (CAN) bus. The computer sets this code when the expected periodic signal from that module goes missing for a calibrated time, not when the heater itself fails electrically.

SystemNetwork

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaLost communication with a control module

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.