How To Replace the Battery in Your Car's Keyless Remote

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Replacing It Is Easy, But What Battery Do I Need?

Replace your keyless remote battery.
The Honda keyless remote has an easy access battery cover, Mercedes does not. © Matt Wright, 2009

In the old days of the keyless remote, usually for an alarm, there could have been any combination of obscure batteries inside. Some things never change. Don't take a chance buying what you think


be the right battery for your remote. If you're lucky, you're remote will have the battery type written on the outside like the Honda unit pictured above. This one takes a 2025 battery. The rest of you will have to either remove the old battery first or put your trust in the Google gods and hope you get good info before you buy it.

Whichever scenario you find yourself in, don't sweat it. We'll show you how to get the old battery out and a new one in without destroying the thing. Mercedes is getting $180 a piece for replacement remotes ... ouch.

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Removing a Battery Cover

Use a coin to remove the battery cover. © Matt Wright, 2009

Turn your keyless remote over (that's the side with no buttons on it). There might be a circle in the back that is actually a battery cover. If you do have such luck, you'll also see an easy way to get this cover off, usually in the shape of a slot that fits a coin. Find a coin that closely fits the slot. Insert the coin and use it like a screwdriver to get the cover off. Don't worry, you won't be electrocuted by your battery.

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In With the New!

This keychain remote takes a 2025.
Check the battery type and placement before you go on. © Matt Wright, 2009

You now have your battery cover removed. Before you tear the battery that gave you weeks of frustration right out of the thing, take a look at how it's in there so you can put the new battery in correctly. Most remotes have a + sign on the side that gets the + side of the battery facing up, but you'd be mad if yours was the remote that decided not to provide that info.

So stick your new battery or batteries in the hole and you're back in business. Congrats!

If your keyless remote looks more complicated than the Honda one, read on to see how a Mercedes Benz (and similar) remote holds its batteries.

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Removing the Battery on Painful Car Remotes, like Mercedes-Benz

Replacing a Mercedes keychain battery.
Slide the lever sideways and pop out the emergency key. © Matt Wright, 2009

If you've read this far you obviously don't have the one-step replacement cover on your car remote. You're at a crossroads. The left fork leads to a life of unlocking your car door with a metal key, the right leads to a difficult but completely do-able battery replacement followed by a year of hands-free bliss.

This procedure covers Mercedes remotes, but the steps are similar for many higher end units.

Here we go:

Step 1: Remove the metal back-up key from the remote unit by sliding its locking mechanism to the side then pulling the key out.

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Disconnect the Top and Bottom of the Keyless Remote Unit

Release the battery holder inside the keyless remote.
Use the emergency key to depress the small button inside. © Matt Wright, 2009

Step 2: Using the metal key, slide a second locking mechanism sideways just inside the unit. There will be a clear notch there for the key end.

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Exposing the Batteries

Out comes the battery holder and guts.
With the button depressed, separate the halves of the remote, exposing the batteries. © Matt Wright, 2009

Step 3: With the latch pushed aside, separate the top and bottom of the remote. You may be removing an access cover or you may be sliding the entire guts out of the keyless remote housing. Either way, get on with it. Remember to do this gently, as you don't want to snag anything fragile or break off any little plastic tabs. There's nothing attractive about carrying a shiny Mercedes remote with a fat piece of duct tape holding it together, believe me. 

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New Batteries Going In!

The keyless remote battery holder.
The battery holder slides out of the bottom part of the key. © Matt Wright, 2009

You've now exposed the batteries. Before you remove them, take a look at how they're in there so you can put the new batteries in correctly. Most remotes have a + sign on the side that gets the + side of the battery facing up, but you'd be mad if yours was the remote that decided not to provide that info.

Replace the battery or batteries as indicated, reassemble the keyless remote, and you're back in business!