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Why your car alarm keeps going off and how to stop it
A properly functioning car alarm is essential for protecting your vehicle from theft and ensuring your peace of mind. However, if your car alarm keeps going off unexpectedly, it can be more than just an annoyance; it can signal underlying issues that need attention. Learn more about the potential causes of car alarm malfunctions and how to solve them below.
Does my car have a factory-fitted alarm and immobiliser?
If you’re unsure whether your car has both an anti-theft alarm and an immobiliser, you can consult the car owner’s manual or check yourself by trying to open one of the car doors after it has been locked. A mechanic can also take a look if you’re still uncertain. Generally speaking, if your car was made after October 1998, it should have its own immobiliser as well as a car alarm system.
All keyless cars will have some sort of immobiliser as this is required to prevent unauthorised use of the car. The alarm and immobiliser should deactivate when the vehicle receives a signal from the key fob chip when it is nearby or when the driver presses the fob buttons. Find out more about the types of anti-theft systems and how they work in this blog.
Why does my car alarm keep going off?
If your car alarm keeps going off for no apparent reason, it is most likely due to some kind of electrical fault. For example, it could be due to faulty sensors or wiring that cause the system to detect false threats. Sometimes it happens because the car battery is running low or is flat, or due to a blown fuse. Thankfully, faulty ones are quickly diagnosed, easy to replace and pick up new car fuses. The alarm can also be triggered due to electrical interferences, temperature changes, and extreme weather.
HELLA Air Horn
BOSCH Horn
12V, 510 Hz, 110 dB(A), Electric-pneumatic, 80W, 80 mm, Holder may need adaptation
BOSCH Horn
12V, 110 dB(A), High Tone, pneumatic, schwarz, 60W
HELLA Fuse
blue, 58V
Car alarm randomly goes off at night
In addition to common electrical faults, such as a low battery, loose connections and bad sensors, car alarms often go off at night as a result of extreme weather or the environment. For example, when there is heavy wind, rain, or thunderstorms, the alarm can be set off or if there are strong vibrations due to heavy traffic and flows of pedestrians.
However, you should also check to make sure that there are definitely no signs of a potential break in or animal activity as this is a time when both thieves and animal invaders are most active.
What causes the car alarm to go off?
Common causes that trigger the alarm:
- Faulty or sensitive alarm system – the sensors can go off by themselves if there is a false signal or due to something as small as a heavy gust of wind, parking on an uneven surface, or a small animal brushing against the car.
- Wiring problems – damaged or frayed wires in the alarm system can create short circuits or inconsistent signals, which can lead to the alarm going off unexpectedly
- Battery faults – a weak or dying car battery can cause fluctuations in the voltage, which might confuse the alarm system into thinking there’s a security breach. In the event of a fault, you should pick up a new car battery.
- Key fob malfunctions – electronic devices or signals from nearby sources can interfere with the key fob’s signal, potentially causing the alarm to go off.
- Environmental and weather conditions – Thunderstorms, heavy rain, and strong winds can all cause vibrations or disturbances that trigger the alarm.
- Animals – windows that are left open, particularly overnight, may allow creatures to gain entry. Some rodents are attracted to the smell of fuel or the car’s warmth.
- Faulty horns – Some may mistake a faulty horn for their alarm. If the horn relay goes bad or the parts are worn, for example, it may go off spontaneously or continuously. If this happens, make sure to install a new car horn unit.
BOSCH Horn
12V, 110 dB(A), Electric-pneumatic, 60W, Holder may need adaptation
TOPRAN Air Horn
with fastening material
HELLA Fuse
80A, black, 32V
HELLA Fuse
20A, blue, 58V
BOSCH Fuse
5A, 32V
How long do car alarms go off for
Most car alarms go off for 30 seconds to several minutes. However, if your alarm goes off for 20 minutes or more, action may be taken against you as this is considered a noise nuisance in most cities.
How to stop my car alarm from randomly going off
Make sure to lock the doors using the key or fob and try turning off the alarm manually. If the alarm is going almost every day then it is most likely due to problems with the sensors or electrics.
Other tips:
- Make sure that the windows are closed at night and the car is parked on an even surface.
- Park the car inside a garage or away from busy traffic if possible.
- Turn off car lights and electronic devices when not in use to maintain the car battery charge.
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