B0258HVAC Air Mix Door 1 Circuit
- Generic OBD-II code · Body
- How the car detects it
- The public J2012 sources do not list B0258, and no carmaker documents it publicly; it cannot be verified. GM's Global A system logs its left, or main, temperature actuator under B0408 instead, as the 2011 Saab 9-5 manual shows. Air mix door 1 is normally the main or driver-side blend door and divides the air between heater core and bypass. In dual-zone units each side has its own doors: Valeo's US6484755B1 places both zone actuators on one side of the case so that one access route serves both. Most actuators are reversible DC motors with a position potentiometer on the gear train, giving a signal between about 0 and 5 V according to MOTOR magazine. A circuit fault leaves the door where it stopped, so the outlet temperature no longer follows the setting.
- What you may notice
- Air from the vents stays hot or cold whatever temperature is set
- Clicking or knocking behind the dashboard when the temperature is changed
- Likely causes
- LikelyBlend door actuator motor or its feedback potentiometer failed
- PossibleActuator plug or wires under the dashboard loose, chafed or shorted
- RareDoor jammed by debris or a broken shaft, overloading the motor drive
- Repair
- Medium · Often possible to do yourself.Typical cost: €80 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.