My car alarm keeps going off. What should I do?

A car alarm not only helps protect your vehicle against theft and vandalism; in some cases it could help lower your car insurance costs.

But what if your car alarm keeps going off for no reason? And what can you do to stop it?

A car alarm not only helps protect your vehicle against theft and vandalism; in some cases it could help lower your car insurance costs.

But what if your car alarm keeps going off for no reason? And what can you do to stop it?

Daniel Hutson
From the Motor team
minute read
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Posted 15 OCTOBER 2021

Why does my car alarm keep going off?

If your car alarm keeps going off and it’s obvious that no one’s trying to break in, it could be due to one of several issues.

Key fob malfunction

One of the most common causes is an entry key fob with a dead battery. If the key fob can’t send the signal to deactivate the alarm system, it can set it off. If the battery’s not to blame, your key fob might need to be reset or scanned with a code reader.

Dirty hood latch sensor

In modern vehicles, the hood latch has a sensor that sets off the alarm if someone tries to force the bonnet open. Over time, dirt, grime and engine grease can build up and stop the sensor from working properly, occasionally triggering the alarm. If cleaning the hood latch doesn’t solve the problem, it could mean a poor connection to the control unit, which will need to be fixed.

Poor installation

Installing an alarm system is one car modification that could help lower your car insurance premiums. But if you’ve fitted it yourself and it hasn’t been installed properly, it could end up doing more harm than good. It could even invalidate your insurance.

Low battery

If your car battery’s running low and isn’t sending the right amount of voltage to the alarm system, it can set it off. Rusty, worn out battery terminals can also be a problem. If the battery’s the cause of your car alarm going off, it’s time to replace it with a new one.

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

Persistent car alarm noise is not only a nuisance for you and your neighbours, it may also be considered a statutory nuisance by your local council. They could issue you with a notice and even forcibly remove the vehicle, charging you with any costs incurred.

So it’s best to get your alarm system checked by a qualified professional. If your car is fairly new and the alarm was factory-fitted, it may still be covered by the manufacturer’s warranty. On the other hand, if it’s been fitted later by you or an unapproved mechanic, your warranty might be void.

Also, be aware that if your car alarm is faulty, it could invalidate your insurance in the event of a claim.

Improve your car’s security

The following tips could help reduce the risk of your car being stolen or vandalised:

  • If you want a post-market alarm installed, invest in a Thatcham-approved car alarm and have it fitted by a qualified mechanic. Don’t forget to inform your insurance provider, as they may offer you a security discount.
  • Don’t just rely on your key fob. Always double-check that your car is locked before leaving it anywhere.
  • Don’t leave any belongings in view, even if your car is locked.
  • Take care of your keys and key fob. Many insurance providers offer key-care cover as an optional extra. This covers the costs of replacing lost or stolen keys as well as re-programming your alarm and immobiliser.
  • Make sure your car is parked securely overnight to minimise risk. 
Did you know?
Ferry companies usually insist you disable your car alarm when travelling with them, as vibrations from the deck can easily set off alarms during the crossing.

Compare and save

A high-quality, professionally fitted car alarm could help lower your car insurance premium. Another way to save money on your car insurance is to shop around. Comparing quotes with us could be the easiest way to find a cheaper deal. 

Frequently asked questions

What is a Thatcham-approved car alarm?

A Thatcham-approved car alarm means that it has been rigorously tested and approved by Thatcham Research, an independent research body used by insurance companies as a benchmark for car security. Thatcham-approved alarms and immobilisers are considered the highest quality and are trusted by car insurance providers, who often offer a discount if you have one fitted.

Can I disable my car alarm?

Most modern cars are fitted with an alarm system shut-off switch. Your manual should tell you where it’s located, but it can often be found near the petrol or hood cap release near your feet. 

That said, most makes and models will deactivate the alarm if you simply lock your car with a physical key rather than the fob. 

Your owner’s manual should have a section on how to deactivate your alarm.

What should I do if a neighbour’s car alarm keeps going off?

Obviously, if you suspect that someone’s trying to nick your neighbour’s car, call 999. But if they have a dodgy alarm that keeps going off, you should let them know that it’s causing a nuisance – calmly, of course. 

If the problem continues, you should contact the Environmental Health team at your local council and they’ll take it from there.

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