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What to do when your car key goes flat
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Electronic car key fobs are great for easy entry to your car, but what happens when the battery dies? Here’s how to get into your car with a flat car key fob and how to replace car key batteries.
Car keys have come a long from the traditional metal key that you physically insert into the car door. Many modern car keys are electronic, allowing you to lock and unlock your car at the push of a button. Some vehicles now come with keyless entry, so you don’t even have to touch the key fob to enter your car.
There are clear advantages to electronic car keys – ease, speed and efficiency – but it can be inconvenient when electronic car key fobs stop working. Here’s how to deal with a flat battery in an electronic car key fob.
How to replace a car key battery when it's not working
My car key fob is flat and won’t work – what do I do?
Older car keys are physical keys that are inserted into locks on the car to open its doors and boot and start the engine. Many modern car keys are remote-controlled by a battery-operated fob. Some even allow for keyless entry and ignition, relying on the car reading the key’s presence on the driver without the need for insertion or clicking a remote.
If your car key remote is damaged or has a flat battery, you need to access its manual key. On modern keys, this key isn’t an everyday necessity, so it’s usually hidden within the fob. The fob may have a mechanical button you can push to flip the physical key out. Other fobs may require you to pull it apart to find the key. Once found, you can use the key to manually lock and unlock your car.
My car doors don’t have keyholes – how do I unlock them manually?
Some newer vehicles have eliminated visible keyholes on their door handles for a sleeker, more modern aesthetic. But the keyhole is still there: just hidden under a cap or cover.
Look on the underside of the door handle or for an embossed key symbol to locate the cap. There will usually be a small cut-away or slot to gently insert the tip of your key blade, which will pop off the cap to reveal the keyhole.
My car has a push-button start – how do I start my car if the key is flat?
If your car has a stop/start button rather than a key-turn ignition barrel, try pressing the button with your key fob rather than your finger. The fob’s magnetic transponder should reach the car and start the engine.
Some vehicles may have a slot for you to put the fob to get it as close to the car’s receiver as possible. This will likely be on the dash, centre console or steering column – your owner’s manual should tell you where to look.
The steering column may also have a hidden slot for the fob’s physical key to be inserted and turned like a traditional ignition.
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Electric car key fobs run on batteries. Image: Getty
How do I replace my car key fob battery?
It’s important to replace the battery in your key fob as soon as possible once it is flat.
Most car key fobs use a standard small, flat, round battery like a CR2032 watch battery that is relatively inexpensive. Key cutters, watch repairers and auto retail stores should all be able to replace your car key fob battery in just a few minutes.
If you need to replace the battery yourself, YouTube is a great resource for finding how to locate and replace the battery in your specific fob. It's important to dispose of the old battery safely, following the ACCC product safety guidelines.
Do my electronic car keys need reprogramming?
If your car key fob’s battery has been flat for a while, you may need to reprogram it. Luckily it can generally be ‘cloned’ from your spare key by an automotive locksmith or your manufacture dealership.
If you’ve lost your spare car key, your car’s computer system may need to be reset to allow for unlocking.
How much do car keys cost to replace?
If you’re simply replacing a car key battery, the battery and service combined should be inexpensive at around $10-15.
Replacing entire car key fobs can be more expensive and cost a few hundred dollars, but it depends on your vehicle make and model.
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If you're locked out of your car, you can call roadside assistance for help.
What are the warning signs for car key batteries about to die?
Telltale signs that your car key battery is dying include:
- the LED light not turning on (on older models that still use a light)
- needing to click the remote multiple times for it to work
- having to stand closer than usual to your car to activate the remote
- experiencing a delay between clicking the remote and your car’s locks responding.
It’s best to replace your car key battery if you notice these signs, so you don’t end up locked out.
Your car may alert you that the key fob battery is low: if it does, replace the batteries in both car key fobs at the same time before they go flat.
Leaving a proximity car key in a vehicle may cause the battery to go flat more quickly. You should never leave car keys in vehicles in order to help prevent car theft.
There is a also a serious risk of the battery getting loose if the fob is damaged, so a repair or replacement should be carried out urgently.
Nothing’s working and I can’t get into my car. What do I do?
If you still can’t get into your car, or if you’ve simply locked yourself out of your vehicle, you can call roadside assistance for help. If you have RACV Emergency Roadside Assistance and the roadside expert is unable to unlock your vehicle, on your request, RACV may arrange for a professional locksmith, when keys have been lost, broken, locked in vehicle or stolen and no spare key is available.*
*For more details about the limits and exclusions that apply, download Emergency Roadside Assistance Terms and Conditions