Mercedes-Benz S-Class key fob battery
12 of the 31 model years listed for the Mercedes-Benz S-Class have a proven battery. The most common answer is CR2025. Rows below run oldest to newest; a year can appear twice when the car came with more than one kind of key.
- 1996-2004Unknown
Not confirmed yet
- 2005Smart key
2 x CR2025
Owner's manual: manualslib.com (checked Nov 1, 2026)
Manual text: “Lithium, type CR 2025 ... always replace both batteries.”
Find CR2025 on Amazon - 2006-2008Unknown
Not confirmed yet
- 2009-2010Smart key
Not confirmed yet
- 2011Smart key
CR2025
Owner's manual: manualslib.com (checked Nov 2, 2026)
Manual text: “You require a CR 2025 3 V cell battery.”
Find CR2025 on Amazon - 2012Smart key
Not confirmed yet
- 2013Smart key
CR2025
Owner's manual: manualslib.com (checked Nov 1, 2026)
Manual text: “You require a CR 2025 3 V cell battery.”
Find CR2025 on Amazon - 2014Smart key
Not confirmed yet
- 2015Smart key
CR2025
FCC ID IYZDC12BOwner's manual: manualslib.com and abkeys.com (checked Nov 1, 2026)
Manual text: “You require a CR 2025 3 V cell battery.”
Find CR2025 on Amazon - 2016Smart key
CR2025
FCC ID IYZDC12BTwo sites agree: manualslib.com and abkeys.com (checked Nov 1, 2026)
Find CR2025 on Amazon - 2017Smart key
CR2025
Owner's manual: manualslib.com and abkeys.com (checked Nov 1, 2026)
Manual text: “You require a CR 2025 3 V cell battery.”
Find CR2025 on Amazon - 2018Smart key
CR2032
Owner's manual: manualslib.com (checked Nov 1, 2026)
Manual text: “You require a CR 2032 3 V cell battery.”
Find CR2032 on Amazon - 2019-2020Smart key
CR2032
Owner's manual: manualslib.com (checked Nov 1, 2026)
Manual text: “You require a CR 2032 3 V cell battery.”
Find CR2032 on Amazon - 2021Smart key
CR2032
Owner's manual: manualslib.com (checked Nov 1, 2026)
Manual text: “You require a CR 2032 3 V cell battery.”
Find CR2032 on Amazon - 2022Smart key
Not confirmed yet
- 2023Smart key
CR2032
Owner's manual: manualslib.com (checked Nov 1, 2026)
Manual text: “You require a CR 2032 3 V cell battery.”
Find CR2032 on Amazon - 2024Smart key
Not confirmed yet
- 2025Smart key
CR2032
Owner's manual: manua.ls (checked Nov 1, 2026)
Manual text: “You need a CR2032 lithium cell battery (3 V).”
Find CR2032 on Amazon - 2026Unknown
Not confirmed yet
Changing the battery
Smart key (push-button start)
- Start by freeing the hidden metal key: there is a latch or slide on the case, and the blade comes out once it moves.
- The gap left by the metal key usually has a pry point. A slow twist with a thin flat tool (tape on the tip saves the plastic) opens the two halves.
- Pop the old battery out with a toothpick or plastic pick, not a metal blade, and seat the new one with the + side matching the old one.
- Close the case until it clicks all the way round, put the metal key back, then try the buttons and a push-button start.
On the common chrome Mercedes key, a slide at the back frees the mechanical key, and pushing that key into the opening releases the battery tray.
This key takes two CR2025 cells. Change both at the same time and stack them the way the old pair sat; mixing a fresh cell with a tired one shortens the life of the new one.
A CR2025 is 20 mm across and 2.5 mm thick. CR2032, CR2025 and CR2016 share the same width but not the same thickness, so a swap between them can leave a loose contact or a case that will not close.
A CR2032 is 20 mm across and 3.2 mm thick. CR2032, CR2025 and CR2016 share the same width but not the same thickness, so a swap between them can leave a loose contact or a case that will not close.
Coin cells are a choking and burn hazard for children. Store the spares in their original pack, out of reach.