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October 10, 2023 Service bulletin

The "SOS nonfunctional" message appears sporadically in the instrument cluster of the vehicle

Mercedes-Benz technical service bulletin LI82.85-P-076800 for 2017-2022 Mercedes-Benz C300, 2017, 2020-2022 Mercedes-Benz E350 and 2017-2022 Mercedes-Benz GLC 300 and others.

Bulletin number
LI82.85-P-076800
Component
Electrical system: instrument cluster/panel
Summary
The "SOS nonfunctional" message appears sporadically in the instrument cluster of the vehicle. The fault code B129C00 is stored in the control unit log. The message occurs in particular after the vehicle has been non-operational for an extended period of time; the message then disappears of its own accord after a few minutes. No functional limitation to the emergency call system is to be expected. Software error in N112/9 control unit for telematics services (HERMES). Software update for control unit N112/9 - Control unit for telematics services (HERMES) to software release E522.8. If, against expectations, the erroneous display of the message in the instrument cluster continues to occur following the update, please create a TIPS case.

Owners of these vehicles have filed 541 complaints in the electrical category.

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