Code Definition

B0423 — Air mix door actuator Circuit malfunction - actuator 2

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

About B0423

B0423 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 B0423 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 B0423 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

The HVAC control module sets DTC B0423 when it detects an electrical malfunction in the air mix (blend) door actuator 2 circuit. On dual-zone climate systems, actuator 2 is typically the passenger-side blend door, working independently from actuator 1 to give each occupant their own temperature setting. The actuator is a small DC motor with an integrated feedback potentiometer; the module continuously monitors both motor drive lines and the feedback signal, and sets this generic circuit-malfunction code when voltage on either line falls outside the normal operating range due to an open, short,...

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