how long does a car alarm go off
Tips & Tricks

How Long Does A Car Alarm Go Off: Everything You Need To Know (Including Shutting Them Up)

It may come as no surprise to you that obnoxious car alarms are one of the most hated attributes of automobiles even when they have been designed for a good reason.

Heck, you may even be someone who has had to call the cops on that obnoxious false alarm or left an aggressive note for your neighbor who left their faulty car alarm ringing all night.

So you are not alone if you are wondering about how long does a car alarm go off – if it even goes off at all. 

While we do not advise you to take any aggressive action – such as taking a baseball bat to the car, leaving an angry note, or the particularly nasty response from some bystanders of leaving feces near the offending vehicle – we do recommend you read on to discover every legal action you can take to address the issue.

In this article, we go over everything you need to know about car alarms. From how long does a car alarm go off, to what to do when a nearby car alarm simply won’t stop disturbing your peace.

How Long Does A Car Alarm Go Off (Things To Consider)

Modern car alarms should generally time out after a few minutes but depending on the design of the car, the model, and your location, it can vary accordingly.

Older car models usually have louder and longer alarm sirens that can keep going for as long as a day. Whereas, a modern car alarm has a more tolerable alarm profile and should shut off automatically after a few minutes.

However, the timeframe also depends on the city you reside in. Many cities now have regulations that allow the alarm to ring for up to 5 or 10 minutes. 

Any longer would be considered a public disturbance for which the car owner could be fined, or even worse, the vehicle might towed out of sight.

A good rule of thumb to follow is the 20 minutes mark. Most vehicles made today should automatically shut off after 20 minutes, regardless of how dire the triggering situation is. Any longer and the alarm should be considered faulty and receive maintenance.

The time frame might be shorter if it is manually shut off by the owner or by an alarm engineer. In any case. hold off on taking action until after the 20-minute mark or until after the time limit set by your home association or local municipality has elapsed.

How Does a Car Alarm Work Anyway?

Car alarms are made up of different parts depending on the car manufacturer but they almost always include a sensor that takes in the physical input of unauthorized tampering

A control unit serves as the brain of the alarm system and the siren or horn emits the sound you hear when the alarm system is triggered.

The control unit not only dictates how long the car alarm goes off, but it also triggers other car components, like the head and rear lights. It also allows you to manually shut down the alarm system using the panic button on the remote key fob.

The sensors are the most important part of an alarm system, though in recent years they have been slightly desensitized to prevent false alarms. These systems are still sensitive enough to trigger the alarm in certain situations, for example:

  • Opening the door from inside.
  • Opening the door when the key fob is not in the vicinity. Key fobs with RFID chips will even prevent the car from starting if a wrong key is used.
  • Undue pressure on the external body of the vehicle, tires, windows, frame. This is triggered by motion sensors when the car is locked.
  • Towing the vehicle. If your car is locked and the key fob is not nearby while the vehicle is being towed, this can trigger the alarm. This is due to tilt and motion sensors.
  • If someone hits your parked car when your car is locked, this can also trigger the alarm system due to the shock from the impact. This is due to shock sensors.

how long does a car alarm go off

Will A Car Alarm Go Off On Its Own?

A car alarm will rarely go off on its own without any signals being sent to its various sensors. However, it can still happen as a result of a malfunctioning alarm system or a faulty key fob.

Back in the 80s and early 90s, car alarms were extremely sensitive. Their motion sensors could be set off by a strong gust of wind or even loud vibrations from a deep bass speaker that manages to rumble the motion sensors.

These cars had alarms that would go off on their own all day and night long. Today, however, due to an increase in other forms of security measures in modern vehicles and the numerous complaints from various advocacy groups, the sensors that trigger alarm systems have been significantly desensitized.

Some of the common reasons why a modern car alarm will go off on its own include:

Malfunctioning Alarm System

The control unit of the alarm system might experience a malfunction, triggering the alarm and sending false signals to the siren. In such situations, you would notice the alarm go off on its own and stop shortly for no reason at all.

Faulty Key Fob

The key fob can also malfunction due to a low battery or an even deeper circuit problem. As a result, it might send false signals to the car alarm system and might also be unable to disable the alarm from the panic button.

Low or Dead Car Battery

If your car battery is critically low or even completely drained, your alarm might be triggered as a signal.

Yes, your car alarm will continue to go off even if the car battery is dead – the alarm is not connected to your car’s main 12V battery.

As part of the anti-theft system, the alarm is instead connected to a separate battery. This is done in case some clever theif decides to remove your car battery before tampering with your vehicle!

Rust, Dirt, or a Short Circuit

Rusty battery cables and dirty terminals can cause your car alarm system to malfunction, or incorrectly make a wrong contact, short-circuiting a connection and causing a false alarm.

What To Do When a Car Alarm Keeps Going Off

If you wait for 10 to 20 minutes and the alarm does not automatically shut off, there are certain steps you can take to resolve the issue as a bystander, a neighbor, or a car owner.

Despite what you may read on Reddit, do not give in to car abuse when your neighbor’s loud alarm keeps going off. Here are some alternative steps you can take:

If You Own The Car

Start by using the key fob to unlock the car. Or press the panic button repeatedly in intervals if that does not work.

If the alarm continues ringing, proceed to start the vehicle with the designated physical key.

You can also check if you have a manual alarm on/off button on your dashboard or around the steering column if you have an aftermarket alarm system.

If all else fails, call a car alarm engineer to shut off the alarm system and possibly replace and fix the system itself.

If You Are A Bystander Or A Neighbor

Feel free to call the non-emergency police department for public nuisance and disturbance.

You can also get the issue resolved if you live in a city where there is a standing resident ordinance on loud alarms that has exceeded a set time frame. They would call the owner to pay fines or even tow the vehicle away, depending on the circumstance. 

If you prefer a more lenient solution, you can leave a note for your neighbor, instructing them to get the alarm fixed.

Frequently Asked Questions

How Long Does It Take A Car Battery To Die When The Alarm Is Going Off?

It takes the auxiliary alarm battery a whole day to be completely drained if the alarm keeps going off. In most cases, the alarm system is not connected to the car battery and will continue to go off even if it is connected to a dead battery or if the car battery is disconnected.

In the case where it is connected to the car battery alone, it will take 24 hours or more to drain the car battery.

Do Car Alarms Go Off If Window Broken?

Depending on if motion sensors or shock sensors are in place, the alarm may either go off or remain completely undisturbed. However, the alarm will almost always go off when the window is broken or if the door is opened from the inside.

Do Car Alarms Turn Off After A While?

Modern car alarms generally turn off after a set period of time, usually in the 30 seconds to 20 minutes range. This depends on the car manufacturer, model, and trigger event.


We all know how annoying loud car alarms can be. With the information provided in this article, you no longer have to sit around wondering, how long does a car alarm go off?

Whether it’s your vehicle or if you are a bystander in this situation, you can take the best action without hesitation. 

For more tips and tricks on your car maintenance see similar articles.