OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Body generic / SAE

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.

SystemBody
Typegeneric / SAE
GroupB0
Range / number2 / 58

Possible causes

  • Air mix door actuator motor failed high
  • Mix door jammed by debris medium
  • Open wiring to actuator medium

Symptoms

  • Warning light or symbol related to the affected system
  • Comfort or safety function impaired

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 80–500 €
  • Estimated time: 1–4 h
  • Component: hvac air mix actuator
  • Component: hvac control module

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication