The car alarm is mainly to deter thieves from stealing your car. However, most of the time, the car alarm will go off when there is no danger nearby.

It is more of a shame than a comfort to the car owner when the car alarm goes off randomly at night. If your car alarm keeps going off randomly, you’re in the right place!

The problem usually lies with faulty sensors, faulty key fobs, or improper installation of the car alarm.

In this guide, you will find all the steps to follow for all car alarm problems so that you can easily recognize and fix the problem as soon as possible.

Let’s start with the guide.
faulty key fob

The key fob is a key component (pun intended) of the car alarm. It tells the car to unlock and also deactivate the car alarm system.

If the remote is low battery or has an error, it can trigger the alarm when you try to open or start the car.

Depending on the design of the key fob and the car model in question, the panic button may be pressed when trying to unlock or lock the car.

Make sure there is no dirt on the key fob as it can cause the panic button to be pressed. Also, a fob that has been in contact with water or any other liquid may be causing the fob to fail.

The best way to test if the keyring is the culprit is to simply try another keyring, if available. If the other key fob works, then the first one is faulty. If not, the problem is probably elsewhere.

A faulty key fob can usually be fixed by changing the battery. Sometimes reprogramming is necessary, which is usually possible at an authorized shop or dealer. If not, a new key fob must be purchased.
faulty sensors

As time goes by, cars are becoming more and more dependent on sensors and computers, and car alarms are no exception.

The car alarm relies on multiple sensors to detect any unusual activity. This includes door lock sensors, crash sensors, hood latch sensors, air pressure sensors, and much more.

Any of the sensors can be a potential cause for your car alarm to go off randomly. Most would need replacement, but there are a few steps you need to take before deciding to replace a sensor, depending on the type of sensor.
Door lock sensors, trunk sensors and hood lock sensors

Door lock sensors, trunk sensors, and hood lock sensors may be faulty, causing the car alarm to sound unnecessarily.

Before eventually changing these sensors, it is recommended to check that each respective compartment is correctly closed. Dirt or debris may be preventing it from closing properly.

This would mean that the sensors are working properly, but the compartment in question may be loose due to dirt or debris. In that case, cleaning it would solve the problem.

However, in most cars this would also inform the driver on the dashboard that these compartments are open, even while driving.

The problem can also lie with debris or dirt on the sensor itself, which is one of the reasons why you should keep your car clean as long as possible, one of the essentials for proper car maintenance.

Shock sensors and air pressure sensors

Car alarms are not only activated when the trunk or a door is opened incorrectly. Shock and air pressure sensors can react to loud sounds, vibrations or breaking glass, triggering the alarm.

These sensors usually cause the alarm to sound when a loud sound is heard or the car vibrates for any reason.

Like the other sensors mentioned, these too can go bad. However, the problem may lie more specifically in the sensitivity of these sensors.

A sensitive sensor that is too sensitive will cause the alarm to go off on unnecessary things. For example, if your car is parked in a garage with a neighbor with a loud exhaust.

Another scenario may be that your car is parked near a construction site or a road with heavy traffic.

If you suspect that the alarm sensors are too sensitive, the best thing to do is visit an authorized mechanical workshop.
Bad car alarm installation

Many people opt for an aftermarket car alarm system in addition to the factory one. This could

It can provide additional security but also problems.

When installing an aftermarket car alarm, it is important to have it done by someone with a lot of experience, as an improperly installed car alarm can go off at any time.

To avoid unnecessary trouble, it is best to purchase a reputable car alarm that is installed by professionals, as many things can go wrong when installing a car alarm.

faulty car battery

A bad car battery can cause a lot of problems, including causing your car alarm to go off randomly at night.

The car battery powers the car alarm, which can alert you that the battery is running low when the alarm sounds.

Related: What size battery do I need? Car Battery Group Size ExplainedBest Car Battery Brands

If you suspect that the car battery is the problem, the most logical thing to do would be to change the car battery.

Fortunately, the sound of the car alarm is not the only indication that the car battery is deteriorating. Other signs, such as a battery warning on the dash, trouble starting the car, dim lights, and more.

Another related problem can be a problem with the battery terminals. More specifically, corroded battery terminals can falsely indicate a problem with the battery itself.

If there is a small amount of corrosion, it can be cleaned with the appropriate agents. If you do, make sure you are sure of what you are doing and prioritize security.
How to turn off a car alarm

The worst thing about having a car alarm go off randomly is not being able to turn it off properly. It is best to always be prepared, which is best done by reading your owner’s manual.

If the manual is of little use, here are some things you can try.
Lock and unlock the car

Usually, pressing a button on the key fob will suffice, but if that doesn’t help, just try manually locking and unlocking the car with the key.

In most cars, there is a small mechanical key inside the key fob that is usually hidden.

Use that key, or your regular key if it’s already exposed, and try locking and unlocking the car through the driver’s door a few times.

If the alarm still doesn’t go off, try starting the car. Sometimes it is even necessary to drive it a few meters.
Remove the alarm fuse

A more drastic approach is to completely disable the alarm by removing the alarm fuse. In this case, the owner’s manual is helpful, as it indicates the location of the fuse box.

Sometimes the fuse box can be difficult to access, so be careful when trying to open it as you may risk damaging parts around the fuse box.

When the fuse has been identified correctly, just remove it and the car alarm will stop immediately.

In some cases, aftermarket car alarms will still go off since the fuse is only used for the factory alarm.

If that’s the case, you can try locating a small box that usually comes with aftermarket alarms and simply unplugging it.
disconnect battery

Battery disconnection should only be done as a last resort. As always, when it comes to electricity and the car battery, be sure to exercise caution and work with protective gear.

There is an excellent guide on wikiHow on how to safely disconnect a battery. It may be that the car alarm works perfectly after being reconnected, but that is a rarity.

Resume

Your car alarm can help prevent thieves from approaching your car; however, many times, the car alarm can go off by itself.

In a car that has a factory-installed alarm, the culprit is often a faulty key fob. Check for dirt or water damage and replace the batteries. If you have another key, try that one.

If the other key fob is also having the same issues, the problem is elsewhere, presumably a bad sensor or bad battery.

Make sure there is no dirt or debris around the sensors or in the various gaps around the doors, latches, etc. If that doesn’t help, the sensitivity of some sensors needs to be adjusted correctly.

If you have an aftermarket car alarm, it has most likely been installed incorrectly and therefore needs to be reprogrammed and/or rewired.

A faulty car battery or battery terminals may also be to blame. If there is a lot of corrosion around the terminals, a simple cleaning will suffice. Note that

other more general symptoms are also usually present.

If the alarm is going off, there are a few ways to turn it off. The first step should be to lock/unlock the car with the key fob. If that doesn’t work, try mechanically locking and unlocking the car a few times.

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