Code Definition

B0428 — Air mix door actuator Circuit malfunction - actuator 3

System: Body  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About B0428

B0428 is a generic (obd-ii standard) body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B0428 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

Because B0428 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

DTC B0428 is a generic body code that indicates the HVAC control module has detected an electrical malfunction in the circuit for air mix (blend) door actuator number 3. On dual- and tri-zone climate control systems, multiple blend door actuators independently meter hot and cold air to different cabin zones, and actuator 3 typically refers to the rear or third-zone blend door. The module commands the actuator to a target position and monitors feedback from an internal potentiometer or stepper-motor pulse count; the code sets when the actuator does not reach the commanded position, the feedback...

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