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Car Alarm Keeps Going Off: What You Can Do To Fix It

Car Alarm Keeps Going Off

One of the most nerve-wracking problems that can happen with your automobile is a car alarm that keeps going off for seemingly no reason. It’s one of these things that demands an immediate solution. If your car is leaking water, that can at least wait until morning to fix. If your car alarm keeps going off, you have to get it taken care of right away because it's so loud and so annoying. There's no other problem with your car that's going to wake you up from a dead sleep at 3 in the morning, not to mention how it's going to make your neighbours feel. But what causes it to happen in the first place? Let's look at the causes that make a car alarm go off and some solutions. 

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Why Does My Car Alarm Keep Going Off?


As with many problems that can arise in a car, there are several potential reasons why your car alarm could be going off for seemingly no reason whatsoever. These are the most common reasons that you should look into if your car alarm keeps going off. 


  • Bad Key Fob. Your key fob or key chain is the electronic remote access device for modern cars. Usually this can lock and unlock your doors, sometimes it will be able to remotely start your engine, and generally it offers you the ability to set your car alarm. Because it operates on a small battery and it's often just sitting in your pocket it has the chance to short out or run low on battery life frequently. That can cause the key fob to send the signal to your car that you want the alarm to go off.

  • Low Battery. If your battery is dying, then your car alarm may be one of the first things to indicate that there's a problem to you. In fact, car alarms are designed to alert you of a dying battery. When you try to start your car with a battery that doesn't have enough power in it your car alarm may go off not accidentally but as a warning sign that there is something wrong with your battery. However, if your alarm is going off just randomly even when you're not in the car it could indicate that the battery is dying or that the connections have corroded and are sending inconsistent power signals throughout the vehicle.

  • Corroded/Bad Battery. Even a fully charged battery can send the wrong signals to the car alarm if it's corroded or dirty in some way. Rusty and worn-out terminals send essentially the same signals as a dying or dead battery to the systems in the car. That can cause any of your electrical systems to malfunction, including the car alarm 


  • Hood Latch Sensor. Manufacturers designed your car alarm to go off if someone lifts the hood who's not supposed to be lifting the hood. This is accomplished by the hood latch sensor detecting the hood moving, it's meant to prevent people from stealing your car or your battery. If the hood latch sensor gets dirty somehow, from road crime or oil, then it will send inconsistent signals and trigger the car alarm to go off.

    Alternatively, the hood latch sensor could be clean but just not installed correctly. If there's a loose wire of some kind or a poor connection the hood latch sensor will malfunction in much the same way as if it was just dirty. It will send the wrong signals to your car alarm that cause it to go off.

  • Poorly Installed Alarm. If you have a new alarm in your car but it seems to be going off for no reason, there's a good chance that the cause is that it was installed incorrectly. Either something is not making a complete connection, or the wiring was done incorrectly, and the alarm system is not receiving the power with the consistency that it needs to maintain proper function.

  • Shock Sensors. One of the ways a car alarm works is with vibration or shock sensors. These can detect when someone is trying to jimmy open your door, for instance. Sometimes the sensors can be overly sensitive, and the result is that an unintentional bump or even something like a cat jumping on the hood of your car can set them off. Ultimately, there are sometimes people who, aware of how shock sensors work, will intentionally vandalize your car by kicking or hitting the bumper with something to set it off. You can do a simple test on your own to see if your car alarm is a little too sensitive by setting your alarm and then giving your car a few gentle bumps to see if anything happens. If the alarm goes off, you may need to have it recalibrated to be a little less sensitive.

  • Accidental Alarm. It may be kind of silly, but the fact is that a lot of times an alarm can go off just by accident. If you keep your key fob in your pocket and sit down funny, or it's out in the open where a pet or maybe a child can get a hold of it it's possible that the panic button was hit by accident and that set the alarm off. Sometimes the most obvious choice is the actual one that works. It's just like when tech support asks you if your computer is plugged in and turned on when you can't get it to work. It may seem dumb but it's the best thing to check when all else fails. 


How Do I Stop My Car Alarm Going Off?


Obviously, the way to stop your car alarm from going off continually depends very much on the reason it's going off in the first place. Symptom by symptom here are some of the ways you may be able to prevent this problem from happening again in the future. 


  • Bad Key Fob. The simple fix for a bad key fob being the cause of your alarm going off is to check and replace the batteries. Your key fob probably uses watch battery, which you can pick up typically at any pharmacy or grocery store. Swap out the batteries and see if that solves the problem if it does then you know the key fob was the issue and you'll know how to address it again if it pops up in the future. Key fob batteries will probably cost you under $5 and they should last for a couple of years.

  • Low Battery. If you suspect the battery is the problem with your car alarm going off, and as we said a good indication that that is the problem will be when the alarm goes off as you try to start the car, it's easy to check. A voltmeter applied to the battery can tell you what kind of charge is in the battery. Anything lower than 12.6 volts is a sign that your battery is just about dead and is going to need to be replaced. A new battery will cost you between $50 and $200.

  • Corroded/Rusty Battery. If your battery still has a good charge but it's the terminals that are corroded or unclean, then you can buy chemical battery cleaner to help clean them up and get a better connection. You'll need to make sure you disconnect your battery first, and then a can of the cleaner might only cost you about $5. Spray it on and follow the directions for cleaning it off and that will hopefully ensure a better electrical connection and put a stop to the alarm going off.

  • Hood Latch Sensor. If your hood latch sensor is unclean, then cleaning it off is a simple procedure. Something like brake cleaner and a brush should be all you need to get it in tip-top condition once more. If you're not sure where to locate your Hood latch sensor, look in your owner's manual. It should be located somewhere near your headlights.

    If your hood latch sensor appears to be clean, you could also try disconnecting it and then reconnecting it again to see if the problem was not that it was dirty but that there was just a loose connection.

  • Poorly Installed Alarm. If you've gone beyond the factory alarm that your car came with you may need to go back to the mechanic who installed it in the first place to get it fixed. Getting a car alarm installed can cost anywhere from $100 to $500. If it was installed incorrectly though, then typically you should be able to get it fixed at no additional charge if this is an issue that popped up immediately after the installation.

  • Shock Sensors. If you test the shock sensors for yourself and discover that simple vibrations such as gentle bumps against your car cause the alarm to go off, you should be able to manually adjust the shock sensor. Shock sensors are usually located on a small control box that can be found beneath the driver side dashboard. This will probably be hidden out of sight because obviously you don't want thieves to be able to see this either. Look around for a small box with a dial and adjust it down to be less sensitive. It could take a little trial and error to get it precisely where you want it. 


Can Wind Set Off My Car Alarm?


It's not unheard of for a car alarm to go off in the middle of some very bad weather. It might surprise some drivers to hear this as they might think that something else must be going on. While it is rare for a car alarm to go off during any kind of extreme weather, as we mentioned, your shock sensors could be a little too sensitive. 


There have been cases in the past when something like a powerful wind has shaken a car enough to set the alarm off. And, of course, if you're in the midst of a seriously damaging storm with gale-force or tornado winds it's no surprise at all that this kind of intense force on your car will set an alarm off. Typically, however you shouldn't expect average, everyday wind to be able to set your car alarm off. If it does happen then check out our suggestions for adjusting your shock sensor to make it a little less sensitive. 

Can I Deactivate My Car Alarm?


Sometimes it's just not possible to determine the precise reason that the car alarm is going off. In those cases you're still going to want to get it turned off as quickly as possible so there are some methods that you can try that may be able to deactivate it until such time as you can figure out what the reason was that it went off in the first place. 


  • Unlock Your Doors. As weird as it sounds, sometimes simply locking and unlocking your driver side doors can do the trick. Some alarm systems can detect when the correct key has been used in the car and turn it off. Just insert the key lock and unlock and see what happens. It only takes a minute and if it works then that'll be much less stressful for you. You can also try this if you have an electronic key fob by pressing the lock and unlock button near the car.

  • Start the Car. The function of a car alarm is to prevent it from being stolen so if you're able to start the car you're telling the system that you're meant to be in there and often getting it started will indicate to the alarm that it needs to turn off.

  • Disconnect the Fuse. In an extreme circumstance you may need to simply disconnect the fuse that controls your car alarm. Check your owner's manual to discover where that is as it could be in the engine compartment or access from the cabin itself. Locate the fuse for the alarm and remove it. If you have a replacement fuse, try popping a new one in and seeing if that solve the problem.

  • Disconnect the Battery. When all else fails, you may have to just disconnect the battery in your car. Make sure you’ve got gloves and pliers or wrench to loosen the nut and remove the negative terminal. If your alarm has a backup battery at me and in fact still keep going but only for a short period of time. Once everything electrical is shut down, let it sit for a few minutes so the computer can reset, and then reconnect the terminal. 


Although it can be very annoying and frustrating to have your car alarm keep going off, it’s also one of the few problems that you can often fix yourself without visiting a mechanic. However, if none of these solutions solve the problem, you may need to get help from a pro.


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