A failed microphone assembly, often due to internal component damage or moisture intrusion.; An open or shorted wire in the microphone circuit, commonly at the overhead console or A-pillar where harnesses flex.; A poor electrical connection at the microphone connector or at the BCM, caused by corrosion or loose pins.; Damage to the wiring harness from rodent chewing, chafing against metal, or pinching during previous repairs.; A faulty body control module (BCM) that incorrectly interprets a good circuit as faulty, though this is less common.; Aftermarket accessories installed improperly, such as a dash camera or remote starter, that tap into the microphone circuit.

DTC codes / B04xx · Airbags, seats, doors, lights and comfort systems / B0450

B0450Microphone Circuit

Q: What does code B0450 mean?

Microphone Circuit. B0450 indicates that the body control module (BCM) has detected an open, short, or out-of-range condition in the microphone circuit, which is typically used for hands-free calling or voice recognition. The computer monitors the circuit's voltage or resistance and sets this code when the signal falls outside the expected range, often due to a wiring fault or a failed microphone.

B0450 indicates that the body control module (BCM) has detected an open, short, or out-of-range condition in the microphone circuit, which is typically used for hands-free calling or voice recognition. The computer monitors the circuit's voltage or resistance and sets this code when the signal falls outside the expected range, often due to a wiring fault or a failed microphone.

SystemBody

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

The hands-free calling or voice command system does not respond to spoken commands.
The radio or infotainment screen displays a message such as 'microphone unavailable' or 'check microphone'.
Callers report that they cannot hear you during a hands-free phone call.
Static, crackling, or intermittent audio is heard by the person on the other end of a call.
Often no symptoms besides the warning light, because the microphone may only be used for certain features.
Voice recognition features may work intermittently or only when the vehicle is stationary.

Common causes, most likely first

A failed microphone assembly, often due to internal component damage or moisture intrusion.
An open or shorted wire in the microphone circuit, commonly at the overhead console or A-pillar where harnesses flex.
A poor electrical connection at the microphone connector or at the BCM, caused by corrosion or loose pins.
Damage to the wiring harness from rodent chewing, chafing against metal, or pinching during previous repairs.
A faulty body control module (BCM) that incorrectly interprets a good circuit as faulty, though this is less common.
Aftermarket accessories installed improperly, such as a dash camera or remote starter, that tap into the microphone circuit.

How to diagnose and fix it

Inspect the microphone connector and the BCM connector for corrosion, loose pins, or pushed-out terminals, and clean or repair as needed.
Check the microphone circuit wiring for continuity and shorts to ground or power using a digital multimeter, following the manufacturer's wiring diagram.
Test the microphone itself by substituting a known-good microphone of the same type, or by measuring its resistance if specifications are available.
Inspect the harness routing around the overhead console, A-pillar, and under the dash for chafing, pinching, or rodent damage, and repair the harness as required.
Clear the code and verify whether it returns; if it does, perform a wiggle test on the harness while monitoring live data to locate an intermittent fault.
If all wiring and the microphone test good, check for technical service bulletins (TSBs) or software updates for the BCM that may address false microphone codes.
As a last resort, replace the BCM only after confirming that power, ground, and all circuit inputs to the BCM are correct and the microphone circuit is intact.

Microphone Circuit Faults Often Misdiagnosed

A common mistake is replacing the microphone immediately, but the fault is frequently in the overhead console connector where repeated use of sun visors or sunglass holders flexes the wiring.
The microphone circuit may share a ground with other overhead accessories, so a bad ground can set B0450 along with other body codes that seem unrelated.
Aftermarket hands-free kits or Bluetooth adapters spliced into the factory microphone wiring are a frequent cause of this code, even if the installation was done years earlier.
Some vehicles use a microphone that contains active electronics, and a simple resistance check will not reveal a fault; only a signal-level test with a scan tool or oscilloscope can confirm proper operation.
The BCM may set B0450 as a history code after a low-voltage event such as a weak battery, and the code may not return after clearing if the underlying circuit is sound.

Can I keep driving with B0450?

The vehicle remains safe to drive because the microphone circuit affects only convenience features such as hands-free calling and voice commands. You can continue driving, but avoid relying on hands-free communication until the fault is repaired, and use a handheld phone only when parked and it is legal to do so.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Reading B0450

BBody: airbags, seats, doors, lights and comfort systems.

0Generic (SAE) code: it means the same thing on every OBD-II vehicle.

4Airbags, seats, doors, lights and comfort systems.

50The exact fault within that area.

Often seen with

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