Noise interference during use of the hands-free system
Topic number

LI82.70-P-079903

Version

4

Function group

82.70 - Telephone, Voice-control-system(VCS)

Date

3/6/26

Validity

Model 465 up to final VIN number ###.###X070207 (production October 20, 2025)

Reason for change

Typographical errors in the text corrected. LI82.70P-079590 --> GI82.70-P-079590

Complaint
Noise interference when using the hands-free system (phone call).

Attachments
File

Description

Beanstandung Störgeräusch.mp4

Complaint about disturbing noise

Cause
The noise is caused by electromagnetic interference (EMC fault) affecting the microphone lines and thus impacting
voice quality.
The severity of these faults may vary depending on the vehicle.

Remedy
To avoid EMC-related interference noise, the SOS microphone line is no longer routed through the rear-installed head
unit (A26/17) but is instead routed directly from the new double microphone to the telematics control unit (N112/9).
The work instruction for implementation is attached to this document and must be completed in full.
Operation steps from the attachment:

•
•
•
•
•

Slide 6: De-pin pins 19 and 6 from plug A at the head unit (A26/17), insulate and strap down. These lines are no
longer needed.
Slide 7: Replace the front left microphone with the double microphone (A213 820 2801) (AR82.70-P-8969XG).
Info: The installation location of the double microphone is always at the front left. There is no difference here between the right-hand drive or left-hand drive versions.
Slide 9: Pin the double microphone wiring harness at connector X58/3X1 at pin 1 (white) and pin 14 (shield).
Slide 10: De-pin the Hermes wiring harness at connector X58/3X1 pin 1 (black line) and pin the white line in its
place. Connect to pin 14 (brown line). Insulate the black line and tie it back.
Slide 15: De-pin and strap down the existing lines at connector 1 on the HERMES (N112/9) from pin 29 (brown),
pin 30 (white), and pin 31 (black).

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© Copyright Mercedes-Benz AG

SAHARRY

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•

Slide 16: Insert the brown line of the new wiring harness at pin 29 and the white wire at pin 30. Connect the
shield (black line) to pin 31.

After completion, please document following FO text in VeDoc: "Conversion to double microphone (A213 820 28 01)
carried out as per LI82.70-P-079903."

Attachments
File

Description

Remedy_Interference Noise Telephony
BR465_EN_V7.pdf
Arbeitsanweisung_Abhilfe schlechte Sprachqualität_DE_V7.pdf

WIS-References
Document number

Title

Note

AR68.10-P-1402XG

Remove glove box

Preparatory work

AR68.20-P-2000XG

Remove center console

Preparatory work

AR68.30-P-1185XG

Remove left load compartment cover

Preparatory work

AR68.30-P-4300XG

Lower the headliner

Preparatory work

AR82.62-P-7839XGM

Bass module speaker

Preparatory work

Disclaimer
NOTE: The information contained in this document is intended for use by trained, professional technicians with the
knowledge to properly and safely perform diagnosis and repairs on Mercedes-Benz vehicles, using Mercedes-Benz
approved tools and equipment. It informs service technicians about conditions that could occur in certain vehicles and
provides information that could assist in proper vehicle diagnosis, service, or repair. It does not indicate that a defect
is present in any vehicle referenced in this document nor does it imply warranty coverage. DO NOT assume that a
symptom or condition, or a described cause of a symptom or condition, affects any particular vehicle or groups of vehicles, or that a described repair applies to any particular vehicle or groups of vehicles. There can be multiple causes
resulting in the same or similar symptoms or conditions described in this document, and trained professional service
technicians must use their diagnostic skills to make evaluations on a case-by-case basis. The information contained
in this document does not guarantee warranty coverage nor does it extend the vehicle’s warranty in any way.

Symptoms
Communication/information > Entertainment > Audio/Sound > Poor audio quality
Communication/information > Communication > Mobile phone > Telephone > Poor understanding
Communication/information > Communication > Mobile phone > Telephone > Other party cannot be heard
Communication/information > Communication > Mobile phone > Telephone > Driver can be poorly/hardly heard
Communication/information > Communication > Mobile phone > Telephone > Person on other end can be poorly/hardly heard

Parts
Part number

ES1 ES2 Designation

A2138202801

06.03.2026 20:37
© Copyright Mercedes-Benz AG

Double microphone

Quantity Note
1

SAHARRY

EPC

Required only for vehicles with a production date up to September 25,
2025.

X

Page 2 / 3

A4658205807

Repair wiring harness

1

Double microphone - OCP

X

A4658205907

Repair wiring harness

1

OCP - Hermes

X

Operation numbers/damage codes
Op. no.

Operation text

06.03.2026 20:37
© Copyright Mercedes-Benz AG

Time

Damage
code

94.0 AW

8210REM

SAHARRY

Note

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