Code Definition

B1D79 — Microphone Input Circuit Malfunction

System: Body  |  Type: Manufacturer-Specific  |  Make: Mazda

About B1D79

B1D79 is a manufacturer-specific body diagnostic trouble code recorded for Mazda vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1D79 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.

B1D79 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Connectivity Master Unit (CMU) or Audio Control Module monitors the microphone input circuit to ensure valid audio signal characteristics are present during hands-free or voice recognition operation. DTC B1D79 is set when the module detects an abnormal condition in the microphone input circuit, such as no input signal, signal outside the expected voltage or impedance range, or loss of communication from the microphone. This indicates the microphone input is not operating within calibrated parameters.

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