2021 Mercedes-Benz AMG GT Phone Call Audio Issues

Owners of the 2021 Mercedes-Benz AMG GT, and potentially other Mercedes-Benz models, may experience a Mercedes-Benz AMG GT phone call issue where their voice is difficult for the called party to understand during telephone conversations. This can manifest as interference, background noises, or a general inability for the called party to perceive the driver's voice, with the problem often worsening as vehicle speed increases. Mercedes-Benz Technical Service Bulletin (TSB) L182.70-P-077433 addresses these audio quality concerns.

Symptoms

Drivers may notice the following symptoms related to the Mercedes-Benz AMG GT phone call issue:

• "Poor understanding" during mobile phone calls.
• "Driver cannot be heard" by the called party.
• "Driver can be poorly/hardly heard" during telephone conversations.
• Interference or background noises audible to the called party.
• Difficulty understanding the driver's voice, which becomes more pronounced at higher speeds.

Fault Codes / Damage Codes

Technicians diagnosing this phone call audio issue may encounter the following damage codes:

Code	Description
82H08EM	Left microphone, difficulties with understanding/interference noise - Please refer to this TIPS document when invoicing.
82W08EM	Right microphone, difficulties with understanding/interference noise - Please refer to this TIPS document when invoicing.

Causes

The TSB identifies several potential causes for the Mercedes-Benz AMG GT phone call issue:

• Improper Microphone Seating: The microphones (identified as B25/20 and B25/21) in the headliner may not be seated correctly. This can occur if the side edges of the microphone are covered by the textile cover, as illustrated in the TSB's Picture 1, which shows a cutout that does not meet specifications.
• Microphone Assembly Issues: Problems with the assembly of the B25/20 or B25/21 microphones within the headliner can contribute to poor audio quality.
• Dirt in Microphone Housing: Accumulation of dirt inside the microphone housing can obstruct sound and lead to unclear audio transmission.

Repair Procedure Summary

To resolve the Mercedes-Benz AMG GT phone call issue, technicians are instructed to perform the following steps for both microphones (B25/20 and B25/21):

1. Access the microphone from the rear, applying pressure with a finger on the adhesive tape.
2. Carefully remove the microphone cap from the front.
3. Inspect the microphone cutout in the headliner for any protruding material residues. These residues must be eliminated, for example, by using a soldering iron, to ensure the microphone can be seated correctly. Picture 2 in the TSB demonstrates the correct seating where the side edges of the microphone are visible.
4. Push the microphone firmly into the headliner from behind until it is securely seated.
5. While maintaining pressure, press and clip the cover cap back into the microphone from the front. It is crucial that the cover cap is clearly heard and felt to engage properly.
6. This entire procedure must be applied to both the left (B25/20) and right (B25/21) microphones.

Important Warnings and Recommendations

• Cover Cap Replacement: It is recommended to replace the microphone cover caps during this repair procedure.
• Non-Woven Cloth: The non-woven cloth located within the cover cap is designed to protect the microphone from soiling and should not be removed.
• General Disclaimer: This document is intended for trained professionals and does not imply a defect in any vehicle or guarantee warranty coverage. Diagnoses and repairs should be performed by qualified Mercedes-Benz technicians using approved tools and equipment.

Owner Action

If you are experiencing a Mercedes-Benz AMG GT phone call issue where your voice is not clearly understood during calls, it is recommended to schedule an appointment with an authorized Mercedes-Benz service center. Explain the symptoms you are experiencing to the service advisor. Technicians will refer to TSB L182.70-P-077433 to diagnose and perform the necessary adjustments or repairs to the microphones.

NHTSA ID: 11008091