B0450Microphone Circuit
- Generic OBD-II code · Body
- How the car detects it
- The code B0450 is absent from the publicly accessible J2012 lists, and no carmaker publishes it, so it remains unverified. Its title covers the hands-free microphone line. The module puts a bias voltage on the signal wire and reads speech back on the same wire. On the 2011 Saab 9-5 and its 9-4X sibling the OnStar module logs B2455 once the signal wire has been broken, grounded or tied to supply, or the low-reference return has lost contact, for 10 s; the status LED turns red and the other party cannot hear the caller. Audio converters like TI's PCM6240-Q1 supply a 5–9 V bias and flag open or shorted inputs and shorts to ground, bias or battery. Calls and voice control still start, but the far end hears nothing. Pairing problems belong to B0440.
- What you may notice
- Caller cannot hear the driver during hands-free calls
- Voice control does not react to spoken commands
- Emergency call or telematics status lamp shows a fault
- Likely causes
- LikelyMicrophone in the headliner or mirror failed
- PossibleMicrophone wire pinched or broken in the headliner or A-pillar
- PossiblePlug at microphone or module loose or corroded
- Repair
- Easy · Often possible to do yourself.Typical cost: €40 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.