U0166
Serious Severity (Level 4)Lost Communication With Auxiliary Heater Control Module
OBD-II diagnostic trouble code U0166indicates a fault detected by the vehicle's onboard computer. This code applies to all OBD-II compliant vehicles and should be addressed promptly to avoid potential engine or emissions system damage.
Severity Level 4 — Serious
This code indicates a serious issue that can cause noticeable driveability problems and potential engine damage if not addressed. The vehicle should be taken to a mechanic as soon as possible. Extended driving is not recommended.
Common Symptoms
- Multiple warning lights
- Gauges may not work
- Vehicle may not start
Possible Causes
- Lost Communication With Auxiliary Heater Control Module
- Fault in related component or circuit
Common Fixes
- Scan with OBD2 diagnostic tool
- Inspect related components and wiring
Estimated Repair Cost
$200 – $1000(typical range; varies by vehicle make and model)
These are estimated costs based on generic repair data. Actual costs may vary depending on your vehicle, location, and labor rates.
Explore Repair Costs
Worried about repair costs?
Get transparent estimates and verify your mechanic's quote before authorizing repairs.
Related Discussions
See what other car owners are saying about this code and related repairs.
View U0166 discussions in the community