B0166
HVAC Discharge Air Temperature Sensor
The HVAC control module reports an implausible signal from the discharge (vent outlet) air temperature sensor. This sensor verifies that the actual outlet air temperature matches the commanded value.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Warning light or symbol related to the affected system
- Comfort or safety function impaired
Common causes
Ordered by how often each turns out to be the cause.
- Discharge air temp sensor failedCommon
- Wiring or connector faultPossible
Parts involved
- Discharge Air Temp Sensor
- Hvac Control Module
B0166 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.