Why Isn't My Car Key Remote Working?

Car key remote fobs are a nice convenience to have, but they all stop working eventually. Even if it's just a dead battery, you can pretty much guarantee that your car doors will fail to unlock with the remote at one time or another.

While there are a few different reasons that a keyless entry remote might stop working, most of them are pretty easy to check yourself. The most common problem with these car key fobs is that the batteries just go dead over time, in which case replacing the battery should fix the problem.

Five things to check when your car key remote won't work illustration
Elnora Turner / Lifewire  

Other key fob remote problems are more complicated, but it's still possible to fix them. Here are the five things you'll want to check first when your remote stops locking or unlocking your car doors:

  1. Verify that the remote is actually bad by using a backup remote.
  2. Check and replace the key fob battery as needed.
  3. Take the key fob apart and check for broken contacts or misaligned buttons.
  4. Reprogram your remote yourself or have a professional do it.
  5. Replace your remote if necessary.

Is Your Car Key Remote Actually Bad?

This is extremely basic stuff, and it won’t apply to a lot of people, but the first step in figuring out what is wrong with a car key remote is to verify that the problem is actually the remote. So if you have a second remote, and you haven’t already done so, you’ll want to check whether or not it works.

If the backup remote is able to lock and unlock your doors, then you’ll know for sure that there’s actually some kind of problem with your main remote.

If your backup remote doesn’t work either, it’s always possible that it is also bad. However, there could also be a mechanical or electrical problem with the door locks.

At this point, you'll want to check and make sure that your physical key, or emergency valet key, is able to work the locks.

If you don't have a spare remote, you may be able to buy a used one or get one from your local dealership. Your local dealership may also have a universal remote they can use to check if your remote lock mechanism works.

What About Cars With No Physical Keys?

Engine Start Stop button in a car
Marin Tomas / Getty Images

Some cars have push-button ignitions that only operate when the key fob is close by. These vehicles still usually have a physical key for locking and unlocking the doors, but it may be hidden. The key fob will often have a hidden key inside, so if you don't have a physical key for your vehicle, then check the fob for a release button or switch.

The other issue you may run into is that some car doors don't have any visible place to insert a key. Most of these vehicles still have a keyhole, but it may be hidden behind a trim piece near the door handle. In that case, you will want to look for a trim piece with a small slot in it, which you will have to pry away to access the keyhole.

Prying away a trim piece like this does carry some danger of damaging the paint on the car door or door handle, and you can also dent or bend the trim piece. So if you aren't comfortable, and there isn't an emergency that requires you to get inside your car immediately, you may want to consult a professional.

If you are able to lock and unlock the doors with the physical key, then the locks are probably fine mechanically. However, there could still be an electrical problem. You can rule part of this out by locking and unlocking all of the doors via the physical primary control inside the vehicle, which would indicate that the electronics are fine.

There is always a possibility that the receiver could be bad, or even disconnected, but it’s more likely that there’s just an issue with your keyless entry remote. You can check behind and under the dashboard for loose wires, but don't connect or plug anything in if you aren't able to verify that it's actually the wireless door lock receiver.

Check Your Keyless Entry Remote Battery

Keyless entry remote keychain fob on a table
 BrianAJackson / Getty Images

Most car key remotes use category 4 button cell batteries that aren’t expensive. However, it’s still a good idea to verify the actual battery your remote uses and check to see whether or not it’s good.

There are a few ways to determine the type of battery you need. It may say in your manual, or you can contact a local dealer. You can also just open up the remote and look at the battery, which will typically have a number printed or stamped into its surface.

Car key remotes typically use CR2025 or CR2032 batteries, although CR1620, CR1632, and others are also used in some applications.

Once you know what type of battery is in your remote, you can either check the voltage with a multimeter or just swap out a known good battery since they aren’t that expensive. Most of these batteries should show about 3 to 3.6 volts.

It's possible for an old battery to show a nominal voltage on a volt meter and still be unable to function under a load. If the battery is more than five years old, consider just replacing it. Even if that doesn't fix the problem, you'll have a safe, fresh battery once you do get your locks working again.

If your car key remote works after replacing the battery, then you’re done. You've fixed the problem, and you can go back to using your key fob as normal.

If the remote still doesn’t work, then there could be another problem with the remote, like broken battery contacts or a problem with the buttons. It’s also possible that your vehicle may have forgotten your fob, in which case you will need to reprogram it.

Broken Internal Contacts in Car Key Remotes

Key fobs are exposed to more physical abuse than most electronics, and they aren’t indestructible. The two most common points of failure are the battery terminal contacts and the buttons, although there are a lot of other ways they can break.

The best way to check this out on your own is to just pull the remote apart again and do a thorough visual inspection. If the battery connector terminals are broken, you should be able to tell by looking at them, and they may also feel loose. If they are, then carefully soldering them back in place may return your broken key fob to useful service.

If the battery terminals don’t look broken, you may find an issue where the buttons are soldered and have come loose. They may be soldered back in place as well if you find that they have come loose unless a button is physically snapped off. In that case, you'll typically need to obtain a new remote.

The rubberized buttons used by most car key remotes can fail in a number of ways. If you notice that one or more of the buttons look like they aren’t popping back out correctly, or they seem to have come apart inside, that can prevent a car key remote from working properly.

In that case, try removing the buttons, cleaning them, flexing them in and out, and then reassembling the remote. If the buttons still don't work, you'll need to obtain a new remote.

Reprogramming a Car Key Remote

In order for a car key remote to work in a secure manner, it has to be effectively paired with the receiver unit in your car. This prevents anyone with the same make and model from walking up and using their fob to unlock your car.

If your keyless entry remote and your car are no longer on speaking terms, you will have to reprogram your car’s keyless entry system to regain your car key remote functionality. This is often accomplished by turning the key in the ignition several times with the doors shut.

Here's the basic procedure for a common key fob programming sequence:

  1. Get in your vehicle, and close the door.

  2. Insert the keys in the ignition.

  3. Rather than start the vehicle, just turn the key to the run position and back to the locked position several times in a row. The number of times will vary depending on your made and model of vehicle.

    If the engine cranks or starts, you've turned the key too far. Only turn it to the run position, not the start position.

  4. In the case that your vehicle uses is method of reprogramming, you will typically hear a chime after you have cycled the key several times. You can then press one of the lock or unlock buttons on the remote, after which you should hear the chime a second time.

  5. If the procedure was successful, your key fob remote will work again.

Different vehicles use different procedures. Here's another one you can try if the first didn't work:

  1. Get in your car and lock the door manually.

  2. Insert your key into the ignition and pull it back out six times within a maximum of just 10 seconds.

  3. If your vehicle uses this method, you will notice the exterior and interior lights flash.

  4. Insert your key into the ignition, and turn it to the accessory position.

  5. Push one button on your remote.

  6. If the procedure is successful, the hazard lights will flash.

  7. Your key fob is now ready to use.

There are other methods, and some require special equipment. In that case, you may have to contact your local dealer or an independent shop that has experience with your particular make and model of vehicle.

If you have an aftermarket car security system that included remote-controlled door locks in addition to an alarm, then you'll need to check for any special reprogramming procedures associated with the system you purchased.

Replacing a Broken Car Key Remote

Keyless remote keychain fob held by a hand with illustration of lock icon on car door
 metamorworks / Getty Images 

If nothing else works, there is always a chance that the receiver inside your car is broken or disconnected. In that case, you’ll probably have to take your car to a professional.

The other option is to just buy a replacement remote, which you can obtain either new from your local dealer or used. If you buy a used one, you will have to reprogram your vehicle to recognize it before it will actually lock and unlock your doors. So if you discovered in an earlier step that your vehicle uses a remote that can’t be easily reprogrammed at home, you’ll want to keep that in mind.

Used car key remotes are typically cheaper than new ones, but costs associated with programming may outweigh the savings.

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