Can you replace car key battery?

Car key fobs are nifty little devices. If you own one, you’ll know there’s a strange sort of satisfaction in clicking the unlock button and seeing your car wink at you from across the street. But aside from the fun of that, key fobs are far quicker to use than traditional keys, and importantly, can help you locate your vehicle in a crowded place — ie. no more wandering about the supermarket car park trying to remember where you left your ride home. Some of the newer smart key fobs can even start your car for you, offering you complete convenience at a click of a button.

Unfortunately, there is just one tiny drawback… The reality of something so small and portable is that a time will come when you need to replace the car key battery. So if you’re clicking desperately and nothing’s happening? And now you’re wondering, can you replace a car key battery yourself? The answer’s yes, and here’s how:

How to replace a car key battery

Luckily for car owners and drivers everywhere, the method for replacing a car key battery is conveniently universal. That’s because the manufacturers have designed their key fobs so that customers can quickly swap out the batteries with minimal effort — so while it’s frustrating to have your car key battery die, the process of replacing it should be relatively pain-free.

Here’s what you’ll need:

Phillips head screwdriver
Flat head screwdriver
A replacement battery (not sure which kind you need? We’ll get to that later)

If you’re not the sort to have a handy toolkit stowed away in your car, you might need to go foraging for screwdrivers at your local hardware store — alternatively, ask a DIY-savvy friend to borrow theirs. The crucial one is usually the Phillips head screwdriver as most car key fobs are sealed with a screw at one end. The flat head screwdriver can often be swapped out if you’ve got strong nails to prise the fob open instead. Once you’ve got the kit you need, follow these steps and you’ll have installed your replacement car key battery in no time:

Remove the key from the fob — this might swing out or detach completely, but in most cases, it’ll be easier to get the fob open with the key removed.
Locate the screw that seals the car key fob and unscrew that using your Phillips head screwdriver. You’ll want to keep the removed screw safe, ie. don’t let it roll off the table and get lost or you won’t be able to close up the fob afterwards! Sometimes there won’t be a screw at all, but a slide, push, or pull opening — have a feel around and find the bit you need.
Most key fobs won’t pop open easily, even when unscrewed, so you’ll likely need to prise it apart (a bit like an oyster). There are two ways to do this… Firstly, you might see that there’s a small coin-shaped slot along the side. If so, slip a coin into it and twist to separate the two halves of the fob. Otherwise, there might just be a line where the fob is joined together. If that’s the case, slip a flathead screwdriver in between to crack it open (or just use your nails and apologise to your manicurist later).
Now you’re inside, check out the battery. It’s likely to be one or two small, silver disks that slide out easily or can be carefully removed using your screwdriver. You’ll find a code on each battery such as CR2025 or CR2032 and that’s what kind of replacement batteries you’ll need. Alternatively, the code might be written on the plastic case underneath the battery or in the car key section of your vehicle’s user manual. The car key replacement battery cost is usually under £10 and you can easily find them in supermarkets, electronic stores, and hardware shops.
Once you’ve slipped the new battery (or batteries) into place, just screw the fob back together, and hey presto! You should be back in action.

But if you’ve followed these steps to the letter and your key fob still isn’t responding? Then keep reading for tips on how to sort out a remote car key replacement.

How to get a mobile car key replacement

Sometimes the car key battery isn’t the problem. If you’ve dropped it, stepped on it, got it wet, or just had it for a really, really long time — then it’s possible your key fob might be ready for retirement.

Thankfully, car key fobs can be replaced via the following methods:

Ask at the car dealership where you bought your car. This can be pricey, around £300 for a replacement key fob, but it’s usually the most reliable option.
Go to an automotive locksmith. Car dealerships tend to outsource keys anyway, so you could get a better deal by going straight to the locksmith. You could also take your old key along to check if there’s no way to fix it.

It’s annoying, sure, but once you’ve got a replacement car key fob you shouldn’t need to do anything but sort a new battery every 3-5 years or so. Just keep it safe, and you’ll be clicking away to your heart's content for years to come.

A few final tips…

If you’re ever in the unfortunate position of having a car key fob stolen, then it’s important that you file a police report asap. From there, it’s a good idea to check with your car insurance company to see whether you’re covered for replacement locks. If your key fob was attached to your house keys, you might also need to get in touch with your home insurance company.

Not sure whether you have home insurance? Check out: ‘Is my house insured?’

If you need to replace more than just a car key fob, you might be interested in: ‘How long does a full car service take?’