What battery does a Mercedes-Benz SLK-Class key take?

Mercedes-Benz SLK-Class key battery

Every Mercedes-Benz SLK-Class remote key we cover, 2011–2016, takes one CR2025.

2011–2016

How to change a smart key battery

Slide the release catch and pull out the emergency key blade.
Wrap the tip of a small flat screwdriver in tape or a cloth, put it in the slot the blade leaves and twist gently to part the case. Keep it off the circuit board and contacts.
Note which way up the old cell sits before you lift it out. It varies by key, so don't assume + is up.
Fit a new CR2025 the same way up, holding it by the edges. Leave any grease on the contacts.
Clip the case back together and test the buttons at the car. Most keys work straight away with no reprogramming.
Keep new and old cells away from children. A swallowed button battery can cause serious injury within two hours.

How to change a remote head key battery

Look for a small screw or a slot along the seam of the plastic head. Undo the screw if there is one.
Wrap the tip of a small flat screwdriver in tape or a cloth, put it in the slot and twist gently to part the head. Keep it off the circuit board and contacts.
Note which way up the old cell sits before you lift it out. It varies by key, so don't assume + is up.
Fit a new CR2025 the same way up, holding it by the edges. Leave any grease on the contacts.
Clip the case back together and test the buttons at the car. Most keys work straight away with no reprogramming.
Keep new and old cells away from children. A swallowed button battery can cause serious injury within two hours.

For locksmiths · R172

Get the transponder chip, the add-key and all-keys-lost procedures, and which of your tools will do it, for every Mercedes-Benz SLK-Class.

Questions

R172 (2011–2016): CR2025 in the smart key and remote head key.

Step-by-step add-key and all-keys-lost procedures for every SLK-Class, which of your tools will do it, and what catches people out.