Why Your Car Alarm Is Going Off But There’s No One Around

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Troubleshooting a car alarm that goes off for no reason
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Car alarms do an excellent job protecting your vehicle from theft, but it can be frustrating when it keeps randomly going off. If you're dealing with a car alarm that's seemingly gone rogue, we've got you! Keep reading for a comprehensive list of the most common reasons why this happens and how to fix each one.

Why does my car alarm keep going off randomly?

The most common reasons why car alarms go off when there's no threat of theft include key fob malfunctions, dirty or faulty sensors, a low car battery, and environmental factors like wind and rain. Less commonly, car alarms can be triggered for no reason if the alarm system was improperly installed.

Section 1 of 3:

Potential Reasons Your Car Alarm Keep Going Off

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  1. Many modern vehicles come equipped with a key fob, or a fob key, used to control cars remotely. A fob can lock, unlock, and even start a car from several feet away. The fob sends a signal to the receiver in the car, giving the alarm system a head’s up that you’re about to enter. A faulty fob could fail to send the signal to your car, triggering the alarm when you approach even though you’re the car’s rightful owner. [1]
    • How to Fix It: A malfunctioning fob could be the result of dead or dying batteries. A quick and easy fix is to buy new batteries. Most fobs contain the coin batteries, available at nearly every place that sells batteries, but check the manual to make sure what batteries your fob requires. You may be able to open the fob up yourself with a screwdriver and swap out the batteries.
      • If the fob is the issue, go to the dealership where you bought your car to replace it; they can also program your new fob. You can call ahead to get a quote, as replacing keys fobs range between $150-$400 on average.
  2. Sensors in your car include door lock sensors, proximity sensors, tilt sensors, and glass break sensors. Each sensor comes with its own set of potential drawbacks. For example, the hood latch sensor may be prone to buildup of dirt and debris, while the door lock sensors are sensitive to water damage, which could affect the entire alarm system. Dirt, leaves, and even small objects could become lodged in the door seals, too. Faulty wiring could also be the culprit, which could require professional repair or replacement. [2]
    • How to Fix It: To make sure your hood latch is not to blame, keep the area clean in and around your hood. In humid or stormy weather, door sensors may be affected. It’s necessary that you address any potential water damage quickly as it could damage your car alarm system irreversibly. For faulty wiring, a mechanic should be able to identify the problem and steps to fix it.
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  3. If you happen to have an older car that didn’t come with an alarm system but you installed one yourself, an improper installation could cause the alarm to go off without warning. It might be tempting to DIY your car alarm as it is a cheaper alternative to getting it professionally installed, but it could lead to complications with your overall system since it’s fairly easy to make wiring mistakes. [3]
    • How to Fix It: If you suspect that a poorly installed alarm is the main problem, taking your car to a mechanic shop could be the best solution. Damaging your car alarm could affect how much you pay for insurance, so trusting a professional to take a look at it and reinstall it if necessary could be a worthwhile investments. Prices for car alarm re-install typically range between $150-$250.
  4. A car battery that’s low in power may not be sending enough voltage to the car alarm system, which could be responsible for randomly triggering the alarm. If you notice your car alarm going off several times throughout the night and you wake up to a dead  car battery, the connection there is evident. Even if the battery is relatively new and appears to be in good shape, the terminals alone might get in the way of the alarm signal. [4]
    • How to Fix It: If your battery is dead, try jumpstarting it for a quick fix. This will stop the alarm from going off and allow you to go about your day in a pinch. However, the longterm fix will to purchase and install a new battery.
    EXPERT TIP

    Ed Beery

    Automotive Specialist
    Ed Beery is an Automotive Specialist and the Owner of InTechgrity Automotive Excellence based in Denver, Colorado. With more than eight years of experience, he specializes in providing maintenance and repair services for both individuals and companies. Ed and the InTechgrity Automotive Excellence Team are approved by the American Automobile Association (AAA) for repairs and are Automotive Service Excellence (ASE) certified.
    Ed Beery
    Automotive Specialist

    Disconnecting the battery will turn off the alarm, but in most cases, you will need a key to open the vehicle and unlatch the hood to disconnect the battery. It is possible to disconnect the negative battery cable from underneath the car in some cases. A car alarm can also be stopped by pulling the correct fuse from the fuse block.

  5. Your car’s surroundings can also play a role in how often its car alarm goes off. Heavy rain, wind, or hail, as well as any other severe environmental conditions could trigger a sensor and the siren. Even noise caused by passing cars or nearby construction zones can create strong enough vibrations in the air to engage the alarm. Your car’s alarm system is actually more sensitive to environmental factors than you may think! [5]
    • How to Fix It: This issue doesn’t require a fix as much as it requires planning and consideration. If your car alarm still goes off in seemingly quiet settings, it could be that your sensors are overly sensitive, which could be a result of faulty wiring. Seek a professional opinion.
  6. This reason is definitely a cause for concern as it points to car theft. When your car is locked and the alarm is activated, the sensors on the door will trigger the alarm if someone tries to enter without a key. This applies to the driver’s side and the passenger’s side, as well as the trunk and hood. The siren’s job is not just to alert you of potential tampering with your vehicle, but also serves to scare the intruder away. [6]
    • How to Fix It: Try to avoid high theft risk scenarios all together by taking certain precautions, like parking in well-lit areas, making sure all doors and windows are locked, and using anti-theft devices like steering wheel locks.
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Section 2 of 3:

What to Do if It Keeps Happening

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  1. If you’ve done everything in your power and your siren still won’t stop going off, it may be that your alarm’s sensitivity is too high. Find out if this is the case by giving your car a slight bump. If your alarm goes off, then, yes, sensitivity is likely the problem. The sensitivity can be controlled on the shock sensor box of a car, which is a small box under the driver’s side dashboard. Simply turn the adjustment dial counter-clockwise, which will reduce sensitivity. This is a better alternative to permanently shutting off your alarm. [7]
  2. If you’ve exhausted all of these tips and tricks, it might be time to take your car in to the shop, just like you’d go in to the doctor’s office if your flu symptoms persisted. In most cases, a volatile battery is a result of faulty wiring, which requires professional attention. Correcting this problem shouldn’t take too long, and you’ll want to do it before this ongoing issue truly starts affecting your life.
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Section 3 of 3:

Can I permanently turn off my car alarm?

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  1. If nothing else is working, your frustration is understandable, but permanently shutting off your car’s alarm is not recommended. Your alarm serves to shield your car and belongings from theft. Additionally, the car alarm can be used in another situations, like to help you find your car in a crowded parking garage or as a call for help in a potentially threatening scenario. However, if you’d still like to turn it off forever— or at least, an extended period of time— you’ll need to look through your car’s manual first in order to find the fuse on the battery that’s connected to the alarm. [8]
    • The location of the fuse can vary depending on the model of the car, but can typically be found underneath the hood.
    • You can use pliers to disconnect the appropriate fuse, which should in turn shut off the alarm’s siren.
    • You should only take matters into your own hands if you have the right tools and experience as you’ll be dealing with electrical currents.

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      References

      1. ↑ https://remotesandkeys.com/blogs/blog/keyfob-key-fob
      2. ↑ https://www.chevrolet.com/support/vehicle/security/arm-advanced-theft-deterrent
      3. ↑ https://reolink.com/blog/car-alarm-system-installation/
      4. ↑ https://www.tireoutlet.com/blog/2980/8-signs-your-car-battery-is-dead-or-dying/
      5. ↑ https://wowowow.com/why-do-my-car-alarm-keep-going-off
      6. ↑ https://www.carparts.com/blog/what-triggers-car-alarms-causes-of-false-alarms-and-faqs/
      7. ↑ https://www.mobile-install.com/blog/entryid/83/what-to-do-when-your-car-alarm-keeps-going-off
      8. ↑ https://www.jdpower.com/cars/shopping-guides/how-to-turn-off-your-cars-alarm

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