This Is Why Car Alarms Go Off (For No Good Reason)

This Is Why Car Alarms Go Off (For No Good Reason)

Ever wondered why car alarms go off for no good reason? Ever woke up at the dead of the night to the sound of a car alarm going off in your neighborhood? Will your neighbors ever forgive you if this keeps going on?

How many times have you gone up to check on your car because alarm went off?

Car alarms are standard features on all modern cars as a deterrent against thieves. They are triggered by vibrations when the car moves. These can be brought about by persons trying to get into your car without disabling the alarm first or when the car is shaken.

Sometimes, the car alarm keeps going off for apparently no reason. This is a common problem for city dwellers. Why does this happen? Well, there could be various reasons. Knowing about them will help you get rid of this annoying problem.

More than 90% of the time, the car gives false alarms. It could just be a passing vehicle heavy enough to rock the car or a dog jumping on the hood triggering that deafening, maddening sound.

What Causes This? (And How Can You Stop It From Happening?)

One of the biggest problems with car alarms is they go off for no reason at all. Because of this, people have become accustomed to the sound and often just ignore it.

It has lost its effectiveness in alerting people about an impending crime from happening.

The problem gets even more frustrating at night when people are sleeping, and suddenly your car alarm goes off without any apparent reason.

Why does this happen? It is not necessary that your car is being robbed, sometimes faulty installation or other reasons also cause the alarm to go off.

Time to figure this out so we can fix it.

Possible Causes Of Why Your Car Alarm Keeps Going Off

There are so many factors leading to a car alarm that keeps going off. And since car alarms have been in existence for a long time, you’ll have to consider the type of alarm you have. Most old cars don’t have them installed as a standard feature.

Newer cars however have it integrated into the car’s system. These are easier to deal with as all you have to do is check the trouble codes in your car alarm control unit with a scanner.

Now here’s a list of possible causes. These are applicable to both old and new cars.

Blame It On The Fob

A faulty key fob is one of the biggest reasons why a car alarm will keep going off for no reason at all. I know, I’ve had the same experience and I had to drive the entire five miles home with a car screaming “Bloody thief” the entire way.

This is a Key Fob. It gets blamed for a lot of alarm related issues. Poor key fob.

A faulty key fob sends an incorrect signal to the car’s alarm system triggering it to go off at inopportune moments.

Check if there’s any physical damage on the key fob. Are there stuck buttons? Cracks?

Have you dropped it recently? This happens to me a lot.

Was it dunked in a bowl full of water? Don’t ask, that happened to me too.

Or do you just need new batteries?

Surprisingly, that’s usually the most obvious reason why your key fob would malfunction. So, always have a spare set of batteries ready.

Does Your Car’s Battery Need A Jolt?

Check your battery’s charge with a voltmeter. If it is lower than 12.6 volts, you will need to recharge or replace your battery.

Turning your engine on with a failing battery will activate the car alarm. 

Is Your Shock Sensor Too Sensitive?

Does your shock sensor trigger the alarm when your pet dog brushes against the car? Do slight ground vibrations make it wail? Do harsh words spoken against the car make it complain noisily?

You probably have a shock sensor that is too sensitive.

Comforting words won’t fix it, but consulting the owner’s manual to find out the proper settings will.

Clean That Dirty Hood Latch Sensor And Make Sure Its Connected Tightly

Check the hood latch sensor for any dust, debris or accumulated grime and clean it. This is usually one of the reasons why car alarms go off for no good reason.

You will need some brake cleaner, a cleaning brush, and a microfiber towel for this. Locate where the hood latch sensor is, you’ll usually find this near the headlights. Remove the battery terminals to reduce the risk of getting an electric shock.

Proceed by applying a thin film of brake cleaner, carefully brushing excess dirt and grime, and wiping a generous amount of it. Reconnect the hood latch sensor before restoring the battery terminals. Make sure that it is connected tightly to prevent false alarms.

If it still goes off, you might have a tampered, damaged, or faulty hood latch sensor to begin with. Have it fixed or replaced immediately.

Are Your Battery Terminals Rusted/Worn And In The Terminal Stage?

Rusty or worn out battery terminals will prevent even supply of power to different car parts. This is also true for the car alarm system. The battery might send out too little or too much power causing the car alarm to go off.

And not just that, you might not be able to start your engine at all because there’s not enough juice to wake the starter up. And now you’re stuck with a dead engine and a triggered alarm.

Do yourself a favor—replace rusted or worn out battery terminals immediately.

Did Someone Mess Up The Correct Installation Of The Alarm?

Yes. This happens. Even factory-installed car alarms can be faulty. If your car alarms go off for no good reason, maybe it’s time to bring it back to the manufacturer to have it checked. They have professional multimeters to do these tasks.

Once correctly diagnosed, they can either replace or repair the faulty car alarm system in your vehicle.

For older vehicles, there are many aftermarket car alarms that you can purchase and have installed in-store to prevent faulty installation.

Deactivating Your Car Alarm (Or The No, No, No Method)

Another way to deal with instances where car alarms go off for no good reason is to deactivate the entire system.

Deactivating the car alarm on an old vehicle. Don’t do this at home. Wear gloves.

For modern cars, deactivating/disabling your car alarm will require software manipulation. For older cars, you can easily disable aftermarket car alarms easily by disconnecting it from the battery.

Remove The Fuse

This is applicable only for older cars because modern cars have car alarms integrated with the Central Electronic Module (CEM). You will have to find the right fuse to remove from the fuse box to effectively do this. Make sure you disconnect the battery terminals first to reduce the risk of electrocution.

Use A Code Scanner

This is how you deactivate car alarms in modern cars. You might need a professional to do this for you as it will require tinkering with the CEM. You can completely disable the unit or lessen the sensitivity so your car alarms go off only at the right times.

Complete Removal Of The Alarm System

You can do this for older cars who have aftermarket car alarms. A partial removal involves snipping the wires, so you can reconnect them in the future. A more thorough approach is removing the entire unit and then wiring from the car system.

Removing your car alarm opens up the opportunities for would-be car thieves to get easily into your vehicle and drive off with it.

Why Keep That Car Alarm? Here Are Some People Who Are Out To Get You

Professional Car Thieves

These are the people who are experienced and hell-bent on getting in your car, no matter how loud that alarm gets. Professional car thieves prefer high-performance cars, but they’re not against stealing regular cars, too. These often end up in chop shops where they take parts out and sell it for a profit.

Some professional car thieves also steal cars for export to other countries. Once sold overseas, it will get harder to trace where your car ends up.


Joy-riders are usually teenagers or young adults looking for some mischief. These people prefer high-performance or luxury cars, but they’re also not against getting inside a conventional car.

These cars are usually recovered, but not without suffering some significant damage.

Although treated as hi-jinks, these instances still cause unwanted stress, repair expenses, and damage to the vehicle. This is still a form of car napping.


Carjacking is another form of illegal activity that happens to car owners. The most effective method is by doing a “Bump-and-Rob”.

A “Bump-and-Rob” is when your car gets hit from behind. The moment you step out to examine the damage, someone is waiting to jump in and drive off.

Sometimes a carjacking is forcibly done when someone just walks up to a stopped car, gets in, and demands the driver to either step out or drive. These carjackers usually have weapons.

Unauthorized Persons

Sometimes cars go missing because an unauthorized person took it without any plan other than to use it in a proper manner with the intent to return it. This can happen with immediate family members, co-workers, and friends. Although the car is returned undamaged (sometimes, hopefully, with a full tank of gas), it can still cause unwarranted stress.

How To Prevent Your Car From Being Stolen

How do you prevent your car from being stolen? Can you make it less attractive to would-be thieves?

The key is to make it highly inconvenient for them to do such a thing. Your alarm is a first step. It immediately alerts people around your vehicle that someone is either forcing their way into it.

Basically anything you can do to hinder their progress is a good way to prevent your car from being taken by car thieves, joy-riders, and other unauthorized persons.

Lock Your Doors Even When Driving

Keep your vehicle locked at all times, even while driving. You’ll never know when someone’s going to try a bump-and-rob. Sometimes, carjackers don’t even have to steal the entire car. All they need is to open the car door and grab all the valuables in plain sight before they run away with the loot.

Never Leave Your Keys In The Car

This is pretty basic. When parked, never leave your keys in the car. Close all the windows and the sunroof. Don’t make it easy for anyone to just get in your car and take whatever valuables you have in plain sight. If you’re unlucky, they can drive off with the entire vehicle since you’ve so kindly left them the keys.

Meet your car’s new owner. Use an anti-theft system next time.

Never Leave Your Car Running Unattended

Never leave your car running and unattended. You’re just asking for trouble when you do this. Don’t even alight from the car while it’s running for a second. All it takes is a small window of opportunity for car thieves to take your car from you.

Don’t Leave Any Of Your Valuables Inside The Car

If we haven’t stressed this enough, don’t leave any of your valuables inside the car. Your car isn’t a locker. It isn’t a vault. You’ve got easy to smash windows. So why would you leave your valuables inside knowing there’s the off-chance someone will get tempted to take them?

Don’t Leave Your Original Documents In The Car

Anyone with an original car title can sell your vehicle. Just keep a photocopy of your car documents inside the car. Hide it in a secure, secret location. Don’t use the windshield visor as a place to clip your OR/CR (Original Receipt/Certificate of Registration). Better yet, leave the originals at home.

Avoid Areas With High Crime Rates (Get Out, Get Out Now!)

Know where you’re going. Avoid known high crime areas even if the alternate route takes longer. This is just a numbers game. Don’t be a statistic. With more criminals around, there are more chances of you getting robbed.

Install An Anti-Theft System (Make Them Think Twice)

Install a car alarm for your older car. Beef up your car alarm system if you have a modern car. Make additional security devices visible like a steering wheel lock. Thieves are always reluctant to try anything with vehicles who are protected and likely to have car alarms go off with the slightest touch.

Park In A Well-Lit Area (The Only Sensible Reason To Be Very Afraid Of The Dark)

Thieves prefer to work in the dark. Be particularly cautious at night about where you park your car. Park it in a well-lit area if possible.

Increase Your Situational Awareness (Unleash Your Inner Chuck Norris)

Look around. Be aware of your surroundings, especially in garages, parking lots and gas stations. You never know who’s lurking in the dark. Make sure you check your periphery before clicking on that key fob or putting the key in. Once inside, lock the doors.

Have Your VIN (Vehicle Identification Number) Etched Into All Windows

Have your car’s vehicle identification number (VIN) etched on each of the windows. Car thieves want to get off cheap. They don’t want to go to the expense of replacing all the glass.

Don’t Kowtow To Their Desires By Letting Them Tow It Away (Making Your Car Hard To Tow)

Park on an incline facing uphill. Leave your car in park or in gear. Turn your wheels toward the curb. Find an obstruction. Put a wheel clamp. This makes it harder for thieves to tow your vehicle.

Types Of Anti-Theft Systems

Steering Wheel Locks

These are highly visible and are good deterrents for car thieves who don’t want the inconvenience of forcing their way into your vehicle only to find out it can’t be driven off. Steering wheel locks often come with bright colors so people can immediately see that it is there. It’s a good visual deterrent. Get one.

Kill Switch

A kill switch is a good anti-theft system that literally disables your car and makes it a very expensive paperweight.

There are two types of kill switches:

Ignition Cut-Off System

Ignition cut-off systems prevent your car from starting even if the person has your keys with him. They can be activated by flipping a switch or by remote through the key fob.

Battery Kill Switch

A battery kill switch is a very discreet module that you can hide anywhere inside your car. It basically acts as a conduit for the battery and the ignition. Once activated, it cuts the connection between the two, effectively “killing” the car. You can deactivate this at any time by flipping a physical switch.

When That Red Blinking Light Is On, It’s Watching.

Passive Car Alarms

These are present on modern cars. These automatically turn on when the key is removed from the ignition. This will activate after it detects a considerable distance between the car and the fob.

Remote Alarm System

A remote alarm can be a passive or active system installed in your car. What it basically does is send out a signal that can be tracked by the police.

In Conclusion:

Car alarms that go off for no good reason may be a nuisance, but they do serve a purpose. They’re a basic deterrent against thieves.

Only the most hardened and determined thieves would continue their dastardly plans regardless of blaring alarms and onlookers.

A car alarm going off continuously can be very disturbing and should be fixed right away, as it may drain your car battery and disturb your neighbors. With the key points we discussed above, you can easily diagnose what is causing the alarm to set off and fix the situation yourself instead of going to a mechanic.

And the next time your car alarms go off, take the time to check. Who knows, your car may not be crying wolf this time.

Related Questions:

What Other Equipment Can I Use To Make Sure My Car Is Safe When Parked In Public?

Aside from car alarms, you can employ a wide variety of safety equipment to keep your car safe from thieves. You can use an engine disabler module to kill your car effectively. No one can drive off with it dead. You can also use tire locks but those are expensive. Or don’t park in public at all.

What Can I Do Against Carjackers?

Nothing. Don’t resist if they already have partial control of your car. No matter how careful you are, some unavoidable things will happen. Determined carjackers will do anything to get your car. You can always replace your car anytime. You only have one life to live. There’s a risk that you could get injured or worse.

Are Car Alarms Still Effective?

Yes. Car alarms, no matter how immune people get to its sound, are still a worthy investment. This is your first line of defense against people who have plans on your car. It might get tiring, but it’s still worth checking your car each and every time the alarm goes off. Or park your car in the garage.

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