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How to Change the Key Battery on a Mercedes-Benz S-Class W221

Model: Mercedes Classe S W221, MK 5 - Years 2005-2013
Part: Key

Often, your car key may malfunction simply due to one or more dead batteries. If you need to replace the button batteries in the smart key of the Mercedes-Benz S-Class W221, don't worry because this guide will provide you with all the instructions to do it correctly. First, remove the physical key, and using it, also take out the small battery compartment. Remove both batteries (or one of them) and replace them with new, fully compatible batteries. Finally, reassemble everything correctly and insert the physical key back into the cover.

Updated on 8 May 2026 by ScegliAuto

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