Mercedes key fob batteries and info

[kevm14]

Thought I'd make a single thread for tracking.

My E63 complained of low battery in the fob. This is a newer style where the back simply clips on. It is released by pushing the key into a catch and releasing the back cover. This fob (no IR transmitter) has one battery. It actually had a 2025 which was kind of loose fitting. I believe it wants a 2032 so I ordered some. I found an old new 2032 to test fit and it needs to be jammed in and then pried out. But a single 2032 sounds right and the general Internet seems to agree.

My S550 uses the older tray style and I believe uses two 2025s.

[rpaoness]

All three of our keys are like that. Single 2032 (20mm dia, 3.2mm thick) is too fat and risks slight bending the back cover and possibly not having the gasket seal well. 2025 (20 mm dia, 2.5mm thick) fits with no issue and is what the Benz dealer put in the new key I bought. I have a 2032 in my gla key since it was kinda more worn inside, but the new GLS key really didn’t close right with one.

[kevm14]

Ended up putting a 2032 in the E63 fob and that worked. Just a tight fit but everything closed up properly.