Why Car Won’t Detect Key Fob?


A remote that isn’t working can be a pain to deal with but there are common problems that can cause a remote to fail. All offer easy remedies 

A car remote may fail because the battery in it is dead, the car battery may be failing, the remote may have failed, or the remote isn’t programmed properly to operate the car. These are some of the reasons why car won’t detect key fob.

A Dead Remote Battery

This is the easiest problem to fix. Most remotes have button batteries that can be purchased at any discount store. The only dilemma is to figure out how to get the battery out of the remote and change it out without breaking the remote. 

You can check your car owner’s manual to figure that out. 

Car Battery May Be Failing

Sometimes, your car battery may be low on juice and that can affect your remote, especially if you are trying to use it to start your car. Check to see if the inside electronics and lights work to determine if this is the problem. 

Read: How Long Can a Car Battery Sit Unused?

Remote Failed

This is something to consider if you replace the fob battery and it still isn’t working. The things that tend to fall apart in a remote are the buttons and the battery terminal contacts. 

It’s easy to figure out if it’s the buttons because they will either stick or come off and you can see that visually. Buttons that don’t pop back when you press them show that they failing. You will know if the terminals are broken by them feeling loose or by looking at them

Reprogramming the Remote

The other problem with the remote could be that it needs to be reprogrammed. Sometimes, the program fails when the battery is disconnected or if you replace the battery in the remote. 

You will need to reprogram the remote to work with your car. Generally, you can do this with the key inserted into the run position and turning it back to the lock position several times. However, the specific way of reprogramming the remote depends on the make and model of the car. 

You will need to refer to your owner’s manual to determine exactly how to do that. 

What You Should Do?

Determining the exact problem means ruling out other problems. Try out these steps before you call a dealer, order a new remote, and do other things that could cost money.

  1. Use your spare remote to open your car. This will determine whether it is your car battery or your remote. This will also determine whether the remote remains programmed to the car. Your spare remote wouldn’t work if it was a programming issue.
  2. You can also use the key in your remote to open your car. This is helpful if you don’t have a spare remote. This might be a little more challenging in push-button start cars but there is a key hidden in the remote that you can use.
  3. Once inside the car using a key, check to see if interior electronics work. That will determine if the car battery is functioning. You can also use the key to start the car so you won’t be hampered with a bad remote.
  4. You have now determined something is going on with your remote. Change out the battery first since that is cheap and easy. 
  5. Try reprogramming the remote to the car once you’ve changed the battery.
  6. You can try opening the remote to check the terminals if the buttons look good. The only problem with that is you could end up damaging it more because remotes are not easy to open and doing so could break the case. 

At this point, you may want to take the remote to the dealer and have them check it out. 

Read: How to Program a Key Fob (For All Cars)


Will a dead key fob make the car not start?

It will not start the start if you are on a keyless car system. Your key fob must be inside the vehicle for it to start the car. A dead battery in the fob means the vehicle’s system can’t recognize when the fob is in the car.

If I leave a car with a keyless ignition on, will it turn itself off if I walk away?

Depending on the make and model, it won’t turn itself off once the ignition is on. However, you can’t start the car if someone left with the keys.

How much does a new key fob cost?

The cost ranges depending on the make and model of the car. A key fob can cost between $150 to $600 to replace. Vehicles that cost more will have a more expensive replacement cost for a key fob. 

That’s because higher-end cars integrate their advanced security systems into their fobs. 

What if my fob unlocks my car but won’t start it?

You could need a new ignition switch or the fob battery is failing. Unlock and lock your car three times and then try to start it. If that doesn’t work or if the car sends a message that you need a key, it’s a tell-tale sign that your ignition switch is bad.

Read: Car Won’t Start But Lights Still Work – What’s Going On?

What does it mean that the key fob isn’t detected? 

Your vehicle saying your key isn’t detected means the car isn’t receiving a signal from a key. This usually means the battery is failing within the key fob. It could be other issues too like the wrong key used, a damaged key rob, or perhaps the fob has water damage.

How do I open a key fob?

Opening a key fob can be a bit tricky because you don’t want to damage the cover. However, all it takes is a flat head screwdriver to do it. Place the screwdriver into the slot on the fob and turn it slightly to pop it. It should open up where you can slip the screwdriver in further to open it completely. 

Make sure you don’t break the connecting plastic attachments that hold the cover together. 

How do I know my key fob battery is dying?

Symptoms of a dying key fob battery are easily recognizable. They include signal strength that weakens over time, it takes you several times to get your car to unlock and your fob doesn’t always work on the first try. Your key fob battery is probably dying if you used to be able to unlock or start your car across the parking lot but now must be next to it.

Can other electronic things interfere with key fobs?

While this isn’t scientifically proven, there is a lot of anecdotal evidence that other things can interfere with how a key fob works. Some possible issues can come up with shopping cart locks, door sensors, Wifi, and some security camera systems.

Do you need to reprogram your key fob if you replace the fob battery?

It depends on the vehicle but, generally, there is no reason why the fob should need reprogramming after you replace the battery. Check your owner’s manual to be sure. 

How long should a key fob last?

The answer to that depends on how much you use it. Those who are constantly going in and out of their cars, use their cars throughout the day for work, school, and kids will need to replace their key fobs soon. 

The average answer of the durability of a key fob is a fob should last between three and five years.


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