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How to Replace the Key Battery of the Mercedes M-Class W166

Model: Mercedes Classe M W166 - Years 2011-2018
Part: Key

If the smart remote of your Mercedes M-Class W166 (2011-2018) no longer works due to a flat battery and you are wondering how to replace it, simply follow the steps in this guide. First, press the button located at the top of the cover and slide out the physical emergency key. Next, use the removed emergency key to detach the rear cover of the remote and then remove the old, exhausted battery. Finally, insert the new one (model CR2025) and correctly refit the cover.

Updated on 9 August 2026 by ScegliAuto

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