B0173
HVAC Air Inlet Door
The HVAC control module has detected a fault on the fresh-air/recirculation inlet door — typically a stuck actuator or position feedback out of range.
- 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.
- Inlet door actuator failedCommon
- Inlet door mechanically bindingPossible
Parts involved
- Air Inlet Door Actuator
- Hvac Control Module
B0173 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.