Code Definition

B1899 — Microphone Input Signal Circuit Open

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

About B1899

B1899 is a manufacturer-specific body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1899 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit.

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.

B1899 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 infotainment head unit, audio control module, or telematics module monitors the input from the cabin microphone, which is used for hands free phone calling, voice recognition commands, and (on some platforms) eCall functions. DTC B1899 is set when the module detects an open circuit on the microphone signal or ground line, meaning the expected DC bias, signal return, or pull up reference is missing. The cabin microphone is typically located in the headliner above the rearview mirror, in the overhead console, or in the A pillar trim, and is connected to the module by a shielded two or three ...

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