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Why does my car alarm keep going off, and how can I fix it?

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If you’ve ever lived in a city, you’ve no doubt been kept awake by a car alarm going off at some point. Even worse is the realisation that it’s your own alarm disturbing the neighbourhood.

That’s why it’s a good idea to know all the different ways your car alarm can be triggered (beyond just thieves) and how you can stop it in the moment.

This extensive guide also takes a look at what you should do if your car alarm keeps going off and the other security features available that may allow you to get cheaper car insurance.

Why does my car alarm keep going off?

Usually, if your alarm goes off, it’s not someone trying to steal your car. Below are some of the most common reasons why your car alarm might go off:

Reason for car alarm going off How to fix it
Dead battery key fob: if your key fob’s battery is dead, it may not be able to send its radio signal to your car. Sometimes, this can cause the car alarm to go off. Replacing your key fob battery should be enough to resolve the issue (although you may also need to reset the fob).
Key fob interference: due to the radio signals key fobs use, your car alarm could be set off by someone else’s key fob or even other devices, such as smartphones. There’s no real fix for this kind of problem, aside from parking in a quieter spot.
Low car battery: if your car alarm goes off for no reason, it can sometimes be a useful indication that your car battery is running low. This is especially true if your alarm goes off when you turn on your engine. You’ll need to get a replacement battery or charge your battery if you have an electric car.
Electrical wiring: if your electrical wiring has become faulty or disconnected, this can trigger your car alarm. You can purchase car wiring diagnostic tools to help identify the faulty connection. If you don’t feel comfortable using a car wiring diagnostic tool yourself, you may need to go to your local garage.
Overly sensitive sensors: car alarm systems are made up of several sensors, such as those in your vehicle’s doors and bonnet. If the sensitivity is too high, the slightest bump could set off an alarm. It may also explain why nocturnal animals such as foxes may be causing your alarm to go off. Depending on the make and model of your car, you may be able to turn down the sensitivity of your car alarm. This should lead to it going off in the event of an attempted robbery but not for a minor movement.
Problems with the bonnet latch sensor: newer cars usually have a car alarm sensor on the latch of the bonnet. If this latch sensor becomes dirty, it can trigger the alarm. Fixing this issue should be as simple as regularly cleaning this sensor. If the issue persists, however, you should check if the latch sensor connection has become faulty.
Poor alarm system installation: if you’ve had a security system installed after you bought it, any issues with your car alarm going off could be related to a bodged installation. If you installed the system yourself, you’ll need to go over your work, check the installation manual and make sure everything is correct. If you paid for an installation, you may need to go back to the person or company and ask for a reinstallation.
Doors aren’t closed properly: if your car door isn’t closed properly, the car alarm may think there’s a problem and go off. Close your doors properly!
Weather and foot traffic: severe weather conditions, such as heavy rain or wind, can trigger your car alarm. Heavy foot traffic can also trigger your alarm if your car is parked in a busy area. Unfortunately, there may not be much you can do about this unless you can park your car in a covered location, such as a garage, or adjust your car alarm sensitivity.

Of course, there’s every chance that an alert is related to an attempted robbery, so it’s always best to check your vehicle if you hear your car alarm going off.

How do I turn off my car alarm?

Different cars and car alarm systems vary in how exactly you’re supposed to turn them off, so it’s a good idea to familiarise yourself with how your specific alarm works whenever you buy a new car or security system.

The following steps may help you turn off your car alarm:

  • Unlock the driver door: some ignition devices have a built-in remote that stops the alarm if you open the driver door
  • Press the “off” button on your dashboard: certain alarm systems may have a physical “off” button you can press on your dashboard
  • Turn on the engine: depending on the cause, turning on your engine may halt the alarm
  • Disconnect the alarm from the battery: if you’re really stuck and cannot figure out how to stop the alarm, disconnecting it from your car battery is an option

What are the risks of disconnecting my car alarm?

You should only disconnect your car alarm from the battery if you’ve run out of options, as not having your car alarm connected can make it easier for your vehicle to be stolen. And if your car is stolen with the alarm disconnected, you may not be able to claim on your car insurance.

What should I do if my car alarm keeps going off?

If you can’t identify the cause of your car alarm going off and it persists, you could be at risk of a nuisance noise complaint.

In that case, it’s important to get your car alarm system checked out by a professional who can advise you on the next steps. You should check your car warranty to see if you’re still covered.

Where can I find information about my car alarm system?

If you want to find out more about your car alarm system, you can:

  • Check the manual: you can check the manual for either the car itself or your new aftermarket security system
  • Ask the dealership or previous owner: if you’re not having any luck with the manual, you could ask the dealership you bought the car from or, if the vehicle is used, its previous owner
  • Take it to your local garage: your local repair shop will be able to help you with any issues you have with your alarm and may be able to give you more information about your security system when you take your car for an MOT

How else can I improve my car’s security?

Alongside your car alarm, there are some other security systems and anti-theft devices you could consider installing. These include:

  • Locking wheel nuts: these devices will prevent your car from being driven away and can only be removed using a special key
  • Brake lock: this device will lock the steering wheel to the brake pedal or clutch, meaning your car cannot be driven without it being removed
  • Car tracking system: installing a tracking system in your car can help you find it if it’s stolen 
  • Dash cams: dashboard cameras can help record any incidents that happen in front of your car

There are also outdoor home security systems you can use to improve the security of your car, including:

  • CCTV: having some kind of camera system installed where your car is parked may help deter potential theft
  • Video doorbells: an electronic video doorbell can similarly act as a deterrent and alert you if someone’s in front of your house

Will installing security devices reduce the cost of my car insurance?

Installing the right security devices may help reduce the cost of your car insurance. However, you should always check with your provider before making any changes to make sure you don’t make any modifications that could invalidate your policy.

Car alarms FAQs

A faulty car alarm may invalidate your car insurance if you try to claim for theft or damage resulting from an attempted theft.

If your neighbour’s car alarm keeps going off, you should first approach them and see if they’re aware of the issue.

If the alarm persists and your neighbour shows no signs of fixing the problem, then you can contact your local council’s environmental health department and submit a nuisance noise complaint.

Thatcham Research is a group that analyses the quality and safety of cars and motor security devices in the UK, including what car insurance group a vehicle falls into.

When it comes to car alarms, looking for one that has Thatcham Security Certification means you can trust it has been rigorously tested by the company’s research team.

There are several different certification categories. The higher the category of the device you install in your vehicle, the cheaper your car insurance premium may become.

Connor Campbell

Finance Writer

Connor Campbell is an experienced personal and business finance writer who has been producing online content for almost a decade. 

Connor is the personal finance expert for Independent Advisor, guiding readers through everything they need to know about car insurance and home insurance. From how much it costs to the best insurance providers in the UK, he’s here to help you find the right policy for your needs. 

In his capacity as writer and spokesperson at NerdWallet, Connor explored a number of topics close to his heart, such as the impact of our increasingly cashless society, and the hardships and heroics of British entrepreneurs. His commentary was featured in sites such as The Mirror, the Daily Express and Business Insider

At financial trading firm Spreadex, meanwhile, his market commentary was featured in outlets such as The Guardian, BBC, Reuters and the Evening Standard

Connor is a voracious reader with an MA in English, and is dedicated to making life’s financial decisions a little bit easier by doing away with jargon and needless complexity.

Amy Reeves

Editor

Amy is a seasoned writer and editor with a special interest in home design, sustainable technology and green building methods.

She has interviewed hundreds of self-builders, extenders and renovators about their journeys towards individual, well-considered homes, as well as architects and industry experts during her five years working as Assistant Editor at Homebuilding & Renovating, part of Future plc.

Amy’s work covers topics ranging from home, interior and garden design to DIY step-by-steps, planning permission and build costs, and has been published in Period Living, Real Homes, and 25 Beautiful Homes, Homes and Gardens.

Now an Editor at the Independent Advisor, Amy manages homes-related content for the site, including solar panels, combi boilers, and windows.

Her passion for saving tired and inefficient homes also extends to her own life; Amy completed a renovation of a mid-century house in 2022 and is about to embark on an energy-efficient overhaul of a 1800s cottage in Somerset.