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    Why Does My Car Alarm Keep Going Off

    Man opening car door

    There are fewer things more annoying that you have to deal with than a car alarm that randomly goes off in the middle of the night, AND IT WON’T EVER SHUT UP. Worse, it keeps on tripping, again and again, and you’re now left wondering… Why does my car alarm keep going off? What can you really do about this?

    Unfortunately, there are many reasons why your car’s alarm keeps going off randomly, whether that’s down to a bad key fob, low battery levels, or problems with your car’s wiring. It’s surprisingly normal for a car’s alarm system to go awry and go off on its own, and that’s particularly so if you’ve installed an aftermarket alarm system. They can be notoriously wonky. Even random things can easily trip your car alarm, such as things inside your car moving around, or someone accidentally bumping their shopping cart into your car.

    With that being said, focusing mainly on specific faults and underlying issues that might be plaguing your car’s alarm system, here are the top 5 reasons why your car alarm keeps going off:

    1. A faulty key fob or remote
    2. Low battery levels or corroded battery terminals
    3. Faulty door, bonnet, or boot sensors
    4. Miscellaneous wiring or electrical faults
    5. Overly sensitive shock sensors

    Here’s a breakdown of each of these common points of failure that continually trip your car alarm, and what you could do about them (plus, a bonus alternative to car alarms at the end):

    1. Faulty Key Fob Or Car Remote

    A malfunctioning key fob or remote can easily send erratic signals to your car’s alarm system. In particular, most car key fobs will have a ‘PANIC’ button (or something similar), which at the press of a button, will set off your car alarm. You can imagine why this might accidentally cause the alarm system to activate randomly.

    Usually, key fobs might do this if their battery level is too low, or if the buttons are worn out or loose, as well as internal electronic/electrical issues within the key fob. This ought to highlight the importance of regularly changing your key fob battery, not to mention making sure you don’t drop it too many times, or leaving it out in the rain to fry its electronics. Additionally, another good trick I’ve learned is making sure you have a spare key fob around the home to swap to, if the one you have now is beyond repair.

    There’s normally not much you can do to fix a broken key fob. Maybe, you could have it reprogrammed, and this might fix any glitches it might have when communicating with your car’s security system. Otherwise, a quick and dirty battery swap might fix it. Most of the time, however, it’s probably safer to just get a new key fob for your car.

    2. Low Battery Levels Or Corroded Terminals

    You may be surprised to learn this, but your car’s security system and the 12V battery have a stronger symbiotic relationship than you might expect. After all, all those alarms and sensors require power from your car battery to activate. So, if you’re wondering ‘why does my car alarm keep going off’, it could be worth just giving the battery a quick check-up.

    Remember, a weak or dying battery could cause the car alarm to go off, as the security system and alarm have detected low voltage from the battery. Additionally, corroded or heavily oxidised battery terminals might also create additional electrical resistance. The latter might lead your car’s alarm or security system to interpret this as a battery issue.

    Fixing this, thankfully, is relatively easy. If your car’s battery is too old (most 12V car batteries won’t last more than 3-5 years), it’s time to replace it. Or, if the battery is still in good shape and has a decent charge left, and you notice a lot of corrosion by the battery terminals, give it a good clean. A clean terminal should ensure a solid connection between your 12V battery and the rest of your car’s electrical system.

    While you’re there, you should also double-check the battery’s voltage level and ensure that it’s optimal, using a simple voltmeter. I’d advise practising a habit of regularly inspecting your battery, and paying attention to your car’s electrical systems to know if it’s time to replace the battery altogether.

    3. Problematic Door, Bonnet, Or Boot Sensors

    A core part of your car’s security system that you might not notice is the myriad of sensors littered throughout. Specifically, we’re looking at the sensors around your doors, bonnet, or boot/tailgate. These numerous sensors help to detect unauthorised access into your car, and if so, it would trip the alarm. It should be no surprise then, that faulty, dirty, or misaligned sensors can accidentally send false signals to the alarm system, letting it go off.

    Typically, you can try to fix this by cleaning the sensors, if you know where to find them. A soft cloth and a good cleaner should be adequate. Or, if you’re willing to DIY further, some cars allow you to adjust the alignment of the sensors, and even check to make sure they have a solid connection. For most cars and their respective human companions, though, it might be easier to just have a technician re-align them or replace these sensors altogether.

    4. Miscellaneous Electrical And Wiring Problems

    Ok, now this is something most regular car owners – not without a good bit of technical know-how – can’t really do much to fix, but it’s worth noting anyway. Electrical and wiring-related faults within your car are easily one of the more common reasons why your car’s alarm keeps going off randomly.

    Damaged, burnt, short-circuited, or frayed wires can create short circuits or send erratic signals within your car’s alarm and security system. This is often caused by wear and tear (a really common issue among older cars), or improper repairs done to your car prior. Alternatively, if there’s a persistent rodent issue at your home, chewed-up wires in your car can cause electrical problems, too.

    For most ordinary car owners, you might be able to whip out a torch and try to locate these damaged or frayed wires in your car. Some minor wiring issues, which might prompt a short circuit to appear, could be fixed with a bit of electrical tape. However, for everything else, professional help is recommended. This is especially true if you’re dealing with serious wiring faults or damage in your car. A mechanic would need to replace the damaged wiring, and if needed, they might have to replace entire systems or sections… Which can be quite expensive.

    5. Overly Sensitive Shock Sensors

    So, remember those sensors I mentioned earlier? Well, there’s another type of sensor that forms part of your car’s alarm and security system… Shock sensors. These help to detect impacts and vibrations that may hit your car, such as someone accidentally bumping into your car. But, in some cases, these shock sensors might have been set a bit too sensitive, allowing the tiniest of impacts to set off your car alarm.

    As such, it could trigger your car’s security system even with minor disturbances, such as another car passing by close to yours, or the neighbourhood cat climbing onto the roof. I’ve also seen some car alarms be triggered by loud thunder strikes, which is another sign that those shock sensors are way too sensitive.

    Some car alarms allow the owner to more easily adjust the shock sensor’s sensitivity. Your owner’s manual may have instructions on how you can do this. If you’re able to do that, try and test different sensitivity levels to find a good balance between keeping your car safe, but also preventing false alarms. If you can’t adjust it, you might have to send your car over to a technician to have them adjust it, or replace the shock sensors entirely.

    What Can You Do About Car Alarms That Keep Going Off?

    Now, if you’re worried that your car alarm is randomly going off far too many times, and if you’re sick of having to deal with it all the time, there is an alternative… Get rid of your car alarm. It’s a bold statement for sure, but there is a method to this madness. Oftentimes, car alarms just don’t work nearly as much as they’re really meant to, and there’s still doubt as to whether they really work at preventing car theft. A lot of the time, when I hear a car alarm go off, my immediate response is, ‘Ah, must be a false alarm’.

    As such, if you’re looking for a more bulletproof and reliable solution to improving the safety of your car at your home, consider installing driveway bollards, instead. They’ve proven to be far more robust and secure at helping to prevent thieves from driving off with your car. Even a fairly simple, affordable telescopic bollard – and we do have a lot of those that we install regularly for clients throughout the UK – that’ll stop a car burglar way better than any car alarm would.

    Consider these points on why a driveway bollard is a far better security system than your car’s alarm:

    • It creates a robust, physical, super strong barrier that prevents thieves from driving off with your car from your driveway. On top of that, you could also use this to prevent unauthorised parking on your driveway.
    • Most driveway bollards don’t have any electronics at all, cutting down on complexity and the risk of something going wrong. Even those that do, like automated driveway bollards, use simple, tried-and-tested electrics.
    • Driveway bollards are a passive security measure, which doesn’t require wonky sensors or alarms to protect a thief from driving away with your car. This also means you won’t have to deal with false alarms at all.
    • Crucially, for the sake of your ears, driveway bollards don’t come with blaring alarms. Even if, by some chance, your driveway bollard suffers from issues, it won’t need to broadcast it with an ear-shattering alarm.
    • Believe it or not, driveway bollards are cheaper over the long run. Sure, the upfront cost of installation is going to eclipse the cost of installing a car alarm. But, over many years, it’ll save you from having to regularly replace your key fob batteries, fix a broken alarm, replace glitchy sensors, or get a new key fob.

    These are just some of the many key reasons why driveway bollards are a far superior method of securing your car at home. And hey, if you’re thinking of installing a driveway bollard at your home, you’re in the right place! We’ve been installing and maintaining security solutions – including driveway bollards – throughout the UK for the past 15 years. In addition to our diverse selection of driveway bollards, we’ve worked with commercial and residential clients, as well as the industrial sector. If you’re unsure of where to get started, don’t hesitate to call us at 01535 920362, and we’ll help you out.