Car key remote control 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 here are a few different reasons that a keyless entry remote control 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.
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:
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.
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.
If your car key remote works after replacing the battery, then you're done. If it doesn't, 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.
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 in place. They may be soldered back in place as well, if you find that they have come loose, unless a button is physically snapped off.
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.