Mercedes-Benz C-Class key fob battery
12 of the 31 model years listed for the Mercedes-Benz C-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
Not confirmed yet
- 2006-2007Unknown
Not confirmed yet
- 2008-2009Smart key
Not confirmed yet
- 2010Smart key
2 x CR2025
Owner's manual: manualslib.com (checked Nov 2, 2026)
Manual text: “always replace both batteries ... Lithium, type CR 2025”
Find CR2025 on Amazon - 2011Smart key
Not confirmed yet
- 2012Smart key
CR2025
FCC ID IYZ-3312Owner's manual: manualslib.com (checked Nov 2, 2026)
Manual text: “You require a CR 2025 3 V cell battery.”
Find CR2025 on Amazon - 2013Smart key
CR2025
FCC ID IYZ-3312Owner'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 IYZDC12BTwo sites agree: abkeys.com and fcc.report (checked Nov 1, 2026)
Find CR2025 on Amazon - 2016Smart 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 - 2017Smart key
CR2025
FCC ID IYZDC12BTwo sites agree: abkeys.com and fcc.report (checked Nov 1, 2026)
Find CR2025 on Amazon - 2018Smart 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 - 2019-2021Smart 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 - 2024-2025Smart key
Not confirmed yet
- 2026Smart 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
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.
- Before you take the old cell out, look at its face. Put the new cell in with the same side showing, and avoid touching both faces at once.
- 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.
If a child might have swallowed a coin cell, treat it as an emergency and get to a hospital right away.