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car alarm keeps going off for no reason

My Car Alarm Keeps Going Off For No Reason

There is nothing more frustrating than when your car alarm keeps going off for no reason and is made even worse when you are trying to sleep. Simply disconnecting your cars battery will stop the alarm but it is not a permanent fix.

Unless you live in a really bad neighbourhood, the alarm is more than likely going to be a false alarm. But how do you stop your car alarm going off on its own for no apparent reason? Below is a list of tests and common causes that will help you diagnose why your car alarm keeps going off.

Hood Latch Sensor Issues

The majority of modern vehicles on the road will have a hood latch sensor that will trigger the alarm if someone is trying to force it open. Due to the design of a car, the hood will collect a lot of dirt and debris, which might find its way to the hood latch sensor. If you look under your hood and see its covered in dirt, cleaning the sensor may resolve your issues.

If you have cleaned the hood latch sensor and still the alarm keeps going off on its own, then you could possibly have a poor connection. If the hood latch sensor is not responding to the cars computer, then the car may react by sounding the alarm as it thinks someone has tampered with the sensor.

The hood latch sensor is a very popular fix for most people and you will be able to find it near the headlights. Many manufacturers differ where the sensor is placed, so it may be best to consult the owners handbook. Below is an example of a hood latch sensor.

clean the hood latch sensor

Incorrect installation of Car Alarm System

If you have recently installed a brand new car alarm system and the alarm keeps going off, then its highly advised that you check the installation. If you have the ability to get your hands on a digital multimeter, this will enable you to check that each wire is getting power and a range of other diagnostic testing.

Stored Alarm Error Code

In order to check for stored alarm error codes, you will need access to a car diagnostic tool. Once plugged in, you should be able to run a quick test that will check for errors related to the alarm system.

If the tests uncover an error with the car alarm system, be sure to read the error code and take note of the issue. Afterwards, simply delete the error message and redo the quick test. If the error code does not appear, this may mean the issue is fixed but if not and the error is still there, you have found the issue.

Faulty Key Fob

The modern day key fob of your car has the potential to cause a variety of issues. From allowing criminals to steal your car via relay crime to sending incorrect signals to your cars computer.

Incorrect signals sent to your car is not one of the most common reasons why your car alarm keeps going off but it is certainly known to happen in a range of cars. If you have tried or tested the other solutions, this may be the cause of your problem.

malfunctioning key fob

Malfunctioning Battery

If your car battery is running low or is outputting an incorrect amount of voltage, this would be one of the first things to change. An alarm will run off the cars battery and in essence, slowly drain it whilst protecting your car.

Therefore, if the alarm is not getting enough power, it may output a false alarm and this may be the case each time it reaches below 12.6 volts. We highly recommend that you invest into new battery for your car for a quick fix. Using a battery charger on a battery that is slowly dying is a lost cause and simply a waste of time.

How To Disconnect A Car Alarm That Keeps Going Off

To prevent your neighbors or anyone around your car becoming very annoyed with your the false alarms, you should learn how to disable the alarm. Below are the four most common methods to disable the alarm system of your car:

  1. Locking and Unlocking the Car – The easiest and most obvious solution is to lock and unlock the car. This is a default way that manufacturers code into the cars computer to turn off the alarm.
  2. Start the Car – Sometimes the above will not work, so failing that you could try starting the car as a way of disabling the alarm system.
  3. Remove the Fuse – If you are fed up of the constant false alarms, you can simply remove the fuse that is used to control the alarm system. We advise that you find it via the owners manual.
  4. Disconnect the Battery – If all the above solutions do not work, you can resort to disconnecting the battery. It is the longest approach but its one that is certain to work as all systems need power.


If your car alarm keeps going off, it is highly frustrating for yourself but your neighbors too. From our research, we have found that the cars that suffer from the most amount of alarm problems include:

  • Honda Accord
  • Honda Civic
  • Lincoln Town Car
  • Toyota Corolla
  • Hyundai Sonata
  • Mazda 6
  • Ford Explorer
  • Toyota Prius

If you own one of these cars, you are not alone with your car alarm issues. Test the above tests and symptoms before contacting a local dealership as they will more than likely do the above diagnostics themselves.

procarreviews author

Written By Dan

About the Author

Dan is an automotive journalist and owner of over 10 cars ranging from supercars, tuned cars, classics and your good old beater cars. He always like to get his hands dirty with nut and bolt restorations or detailing sessions using the best products on the market.

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What Are Your Thoughts?

  1. I have a mk4, & my driver side door gives me an open door on my dashboard. maybe that’s why my alarm keeps going of every time I look my car.

  2. I have a 2009 Chrysler Sebring. A few times my car alarm has gone off for no reason. What happens more often is at times when I turn the ignition off, open the car door, the radio continues to play, the head lights/wipers also manually need to be turned off.

  3. I have a Chevrolet Optra and recently was in an accident. The bonnet doesn’t close properly. The alarm keeps on going off and its so frustrating.

  4. I have a Honda Civic Hybrid alarm goes off 8 times odd hours during the night. Tried unlocking and locking the car. It worked for a few hours then start up again. Even checked the fuses it’s not burn out. Also changed the battery on the key remote. Problem still occurring.. Manually locked car. It’s a temporary fix. What else would you suggested to fix the problem?

  5. Hey Betty – It does look like you have already done the obvious. If possible, you could plug the car into a diagnostic tool? This may throw an error code that leads you straight to the issue. The last thing you will want to do is put loads of money into fixes without knowing if its the actual cause of the issue.

  6. I parked my Toyota Corolla (2009 model) in my compound by 2PM in the afternoon, I was surprise that by 1AM at night my neighbor came to knock my door that my car alarm went off, I was surprised because the car has been parked there since the afternoon. What will cause the alarm to go off in the middle of the night. The car doesn’t have extra alarm just the one that works with the fob.

  7. Hey Mandy – What is the health of your battery? Sometimes those that are low can trigger this sort of behavior. If you have a diagnostic tool available, plugging this is may give you an error code relating to the alarm going off too.

  8. My 2018 Honda Civic EX Gave me same thing today, I tried every thing and failed. Then I tried reopening my all windows and then closed all properly. Then every thing came to Hold. Job Done

  9. I have a ford escort, we had just replaced the front axle. Now the cars alarm keeps going off. It varies of when it does it but it’s getting frustrating and driving me insane. I can’t figure out if it’s the fob or what!

  10. Hey Jess – This to me seems that the sensor (either tilt or shock) may have been triggered as the car was jacked up in the air in order to change the axle. Could this sensor become damaged during the replacement axle?

  11. Im going through a similar thing. I have a 2017 Honda Coupe Ex-T and my alarm has been going off two days straight for at least twice a day at different times throughout the day. My car has been parked and locked while the alarm has gone off. When I go to turn the alarm off I cant use my remote, but I have to use my manual key. I had to get a new battery because my battery was done, shot. I am trying to figure out what is the cause.

  12. I have 2015 Dodge Grand Caravan and my mechanic just changed my spark plugs and one ignition coil. After a few days my alarm goes off without any reason at any time of the day on parking. Any opinion? Thanks.

  13. My Opel insignia has developed a problem with the alarm. The garage could not find anything wrong with it so I Brought it home and once again the alarm went off when I locked it with the key fob. I am now locking it with the manual key. Would appreciate your comments!

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