How to unlock your car when the key battery is dead

• Moving closer to your car may allow a weak key fob battery to unlock the vehicle. Alternatively, use the physical key hidden within the fob.
• Check whether your car has remote unlocking via apps or the manufacturer’s support centre.
• Ultimately, replace the key fob battery – CR2032 and CR2025 are the most common batteries.

You’re about to set off, but just as you approach your car, you find the key fob is dead. 

A dying or dead car key battery is a major headache for any driver and certainly an impediment to your day. Luckily, there are actually a few tricks you can try to get your car started without it. 

Unlocking and starting your car with a dead car key battery 

Here are some ways to get around the problem when your fob battery is not working: 

• Move closer: The first thing you should try is to move closer. If the battery isn’t dead completely and still has a little juice left, it may just take the simple act of standing closer to open it. 
• Manual opening and starting: In the age of technology, we sometimes forget that manual opening is still an option for us. Many key fobs will have a physical key tucked away within them that can be released at the push of a button. This can be used to unlock the car in the event of a dead battery. 

Once in the car, modern vehicles with a start button often use radio wave technology allowing you to start the ignition without the need for key battery power. Try placing the key fob near the start button for ignition. Failing that, look for a backup slot where the key fob can be physically inserted.

There will still be plenty of vehicles on the road where physical ignition slots are the default, meaning you simply insert the manual key to get going. 

• Remote unlocking: If you don’t have the option of using manual car opening and ignition, you can look at the option of remote unlocking. Investigate if there is an app or online method of remote unlocking linked to your car. If you struggle with this, you may need to contact the manufacturer to see if they can remotely unlock the vehicle from their side. 
• Call roadside help: If none of the above is working and you are stuck with a car that you cannot open, you’ll need to call roadside help. 

• Get a new battery: Irrespective of the workarounds above, you’re going to need a new battery to return usual functionality to unlocking and starting the car…

How to replace a car key fob battery 

Sometimes all it will take is to open up the back of your car key with a screwdriver. There are a few commonly sized batteries – CR2032 and CR2025 for instance – but it’s worth checking in advance of purchasing a new one.

If this is proving too tricky, then take the fob along to a car parts retailer who should be able to replace the battery for you. It might turn out that the battery wasn’t the issue all along and that the fob itself is faulty. In these cases, the car manufacturer will be able to arrange a replacement. 

Keep your car in roadworthy condition with help from Mr Tyre. We’re the leading chain of autocentres for Central England, known for our friendly and affordable services. From expert tyre fitting to MOTs and diagnostics, we take care of thousands of vehicles across our 36 branches. Simply give us a call to find out more.