B0258
HVAC Air Mix Door 1 Circuit
The HVAC controller reports a fault in the actuator circuit for air mix door 1, which controls the proportion of warm and cool air in the airflow.
- 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.
- Air mix door actuator motor failedCommon
- Mix door jammed by debrisPossible
- Open wiring to actuatorPossible
Parts involved
- Hvac Air Mix Actuator
- Hvac Control Module
B0258 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.