B0170
HVAC Mode Door Position Sensor
The HVAC control module reports an implausible position signal from the mode (air distribution) door feedback sensor. Without valid feedback the actuator cannot be regulated to the correct position.
- 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.
- Mode door position sensor failedCommon
- Wiring or connector fault to actuatorPossible
Parts involved
- Mode Door Position Sensor
- Mode Door Actuator
- Hvac Control Module
B0170 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.