AutoCodes – Generic – B127C:1A

B127C:1A Code - Microphone 2 Input Signal Circuit Signal Performance

Quick Answer

The active noise cancellation system uses three microphones in the vehicle headliner: one above each front seating position, and one above the rear seat. Common causes include Faulty Radio Volume Compensator Interior Noise Microphone, Radio Volume Compensator Interior Noise Microphone harness is open or shorted, Radio Volume Compensator Interior Noise Microphone circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: B127C:1A indicates Microphone 2 Input Signal Circuit Signal Performance.
Common causes: Common causes include Faulty Radio Volume Compensator Interior Noise Microphone, Radio Volume Compensator Interior Noise Microphone harness is open or shorted, Radio Volume Compensator Interior Noise Microphone circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 185

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Nov 29, 2024

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code B127C:1A Description

The active noise cancellation system uses three microphones in the vehicle headliner: one above each front seating position, and one above the rear seat. The Audio Amplifier provides a bias voltage to each microphone (+) and (-) signal circuit for the operation of the microphone. The microphones monitor the vehicle cabin for undesirable engine sounds. The Audio Amplifier uses the microphone inputs and an engine RPM signal to determine the frequency of the undesirable sound. The Diagnostic Trouble Code (DTC) will be set when an out-of-range voltage is detected on the specified (+) or (−) signal circuit for more than 1.5 seconds

OBDII Code B127C:1A - Microphone 2 Input Signal Circuit Signal Performance - AutoCodes.com — B127C:1A Code - Microphone 2 Input Signal Circuit Signal Performance

What does this mean?

What are the Possible Causes of the DTC B127C:1A?

Faulty Radio Volume Compensator Interior Noise Microphone
Radio Volume Compensator Interior Noise Microphone harness is open or shorted
Radio Volume Compensator Interior Noise Microphone circuit poor electrical connection
Faulty Audio Amplifier

How to Fix the DTC B127C:1A?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

Installation of aftermarket replacement speakers, additional speakers/subwoofers, or aftermarket exhaust systems can cause undesirable behavior of the active noise cancellation system. The noise reduction microphones have foam blocks above them to seal the microphones and aid in the reduction of headliner vibration. Missing or out of place foam blocks can impact system performance.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B127C:1A code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B127C:1A Code

What does the OBDII code B127C:1A mean?

The code B127C:1A indicates a performance issue in the Microphone 2 Input Signal Circuit, suggesting the microphone signal is outside its expected parameters.

What are common symptoms of code B127C:1A?

Symptoms may include reduced voice recognition performance, inability to use hands-free calling, or poor audio quality during microphone use.

What causes the B127C:1A code to appear?

The code can be triggered by a faulty microphone, wiring issues, connector problems, or an internal failure in the audio control module.

How do I diagnose the B127C:1A code?

Start by inspecting the microphone and its wiring for damage, check the connectors for corrosion, and use a scan tool to verify related live data.

Can the problem with code B127C:1A affect other features?

Yes, it can impact features like voice commands, hands-free calling, and other microphone-dependent functions.

How do I fix the B127C:1A code?

Repair steps include replacing the microphone if faulty, fixing damaged wiring, cleaning or replacing connectors, or updating/replacing the audio control module.

Is it safe to drive with code B127C:1A?

Yes, the code doesn't affect vehicle drivability but may limit hands-free or voice command functionality, which could be inconvenient.

Can a software update resolve the B127C:1A code?

In some cases, a software update for the audio control module may resolve compatibility or calibration issues causing the code.

How can I prevent the B127C:1A code?

Routine inspection of wiring and connectors, avoiding physical damage to the microphone, and keeping the audio system firmware up to date can help prevent this code.

Do I need professional help to fix the B127C:1A code?

While some issues like wiring repairs can be DIY, diagnosing and fixing module-related problems may require professional equipment and expertise.