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How to Reset a Car Alarm

How to Reset a Car Alarm

How to Reset a Car Alarm


What is a car alarm?

How do you reset a car alarm?

Are you currently dealing with, or have you ever wondered what would happen if your car alarm started to go off by itself? Have you ever been unable to start your vehicle due to a triggered theft event? In this article, I am going to first cover the basics of modern vehicle alarms and anti-theft systems. Then I will go through the basic procedure highlighting how to reset a car alarm. Some theft faults can be more specific and will require either a diagnostic tool or a repair shop.

If there are any specific issues you are having, or you have a question you would like answered, please be sure to comment at the end of the article!

Vehicle Anti-Theft and Alarm Systems:

Reset a Car Alarm


Modern vehicles are all equipped with smart security systems. Most of us know by now, even the most complex electronics fail at times and can leave us stranded. These systems can contain a lot of different modules/sensors/wiring etc, therefore leaving a lot of room for failure. When everything is working correctly, these systems are awesome to have on your vehicle.

The security systems in vehicles consist of multiple wireless signal senders and receivers. Most car keys are encrypted with a signal chip inside of them. If they are ‘smart keys’ then the chip will be inside of the fob/key assembly and it will all be one piece.

The systems are designed to trigger the security system if the vehicle is started without using the proper key/fob. When this happens, the vehicle will inhibit the engine from starting and often times it will trigger the car alarm/horn. The system can have faults due to something as simple as a dead fob battery, all the way to a bad engine control module.



Identifying a Theft System Issue:


One of the more annoying parts about theft system issues is they will usually appear randomly, and then it can be tricky to figure out why all of a sudden your car will not start. Usually, if the vehicle will not start due to a theft system issue, you will see a theft icon illuminated in the dash cluster and know the direction needed to go.

Reset a Car Alarm

Some vehicles do not have an actual theft light like in the picture, instead, they use a small red LED. This will be either in the cluster or in the left side upper corner of the dash.

Most security systems operate using different radio frequency signals. I have seen theft systems act up due to aftermarket accessories in the vehicle. A big one with some of the newer systems is the police radar scanners. I have had two 2018 trucks with key fob detection issues while there was a radar scanner installed. So, heads up if that is something you see.

Older systems often have a ‘valet’ switch that can be used to reset the alarm and theft system.

Aftermarket alarm systems and remote start systems can cause a big problem as well. For some reason, if you decide you are going to get an aftermarket system installed, PLEASE be sure that it is done by a qualified installer. You don’t want to pay an installer to put it in, and then pay a technician to diagnose an alarm system issue later on. See the photo below for an example of a bad installation.


Bad Car Wiring


Resetting the Alarm:


How to Reset a Car AlarmFirst, be sure you have tried both available keys. If you have tried your available keys, then you can attempt to reset the system by disconnecting the battery. Once you have it disconnected, perform a module reset and touch the positive/negative cables together to make sure any remaining voltage leaves the system. Leave the battery disconnected for ten minutes.

After reconnecting the battery, use the key fob to lock and unlock the vehicle. Once inside the vehicle, turn the key to the on position for 10-seconds before trying to start it. Watch and see if the theft light turns off. If the light turns off and is no longer on, then the system should be reset and clear of faults.

If the security system light is still active, then it will need to be hooked up to a scan tool that is capable of reading the theft module data. It could be a bad key, fob, receiver, module or wiring issue, the trouble codes would at least help point in the right direction for proper diagnosis. If this is not something you are comfortable with, call and schedule a mobile mechanic or qualified locksmith. Worst case scenario it can be towed to your service shop of choice and be diagnosed and repaired there.

I hope this has helped you gain a better understanding of the car alarm system and how to reset it. Please leave any comments and questions below! Learn about different Warning Lights HERE.


  • mahadihassan1 says:

    First of all, I want to give you thanks for such an excellent blog. you have shared such an amazing topic because a few days ago I bought a new car so I don’t have any idea how to reset the car alarm until after seeing your article. I got a lot of information about that and I am following your instruction. I just want to say that your article is extremely beneficial to me and thank you so much for the help.

    • Gabriel G. says:

      You are very welcome! I am glad you found the information useful 🙂 Feel free to reach out if you ever have any questions about your new car

  • Trevor says:

    How many times have I been disturbed by neighbours and their car alarms?  Too many to count. And sometimes they are genuinely trying to “stop” the **** alarm but can`t. Your niche site provides a really useful service; indeed I have bookmarked it.  Just in case…and I can share it with those neighbours I refer to above. I particularly appreciate how CLEARLY you describe the process. Typically, technical manuals are just, well, for technicians or mechanics.  You clearly have some great experience and you have explained things in a way a layman or laywoman could understand. Thank you.

    • Gabriel G. says:

      You are very welcome Trevor. I know exactly what you mean, it used to be a nightmare when we lived in an apartment complex and people’s alarms would go off all the time, so frustrating!! Thanks for bookmarking 🙂

      I am glad you got an ‘easy to use’ feeling from the write-up. That’s my goal, to make things simple and easy to understand for anyone who may be in a bind, or people who want to learn some new info. Take care!!

  • Naksh says:

    Your guide is very useful, thank you. While reading I was able to learn a lot about how car alarms work. I knew that most car keys are encrypted with a signal chip inside of them, but had no idea what to do in case I had an issue with it. Next, I will need my own scan tool!  Thanks for sharing such useful guide.

    • Gabriel G. says:

      I am glad you were able to learn something new about how car alarms and theft systems operate! Let me know if you ever have any questions!

  • Fiona says:

    Thank you for sharing this informative and helpful article about How to Reset a Car Alarm. I would like to thank you again for sharing this helpful information, l have been having issues with the alarm that was stored in my car and every time l wake up every morning l get a message that tells me there is a Possible remote jamming detected in the area (on my car registration plate ) please ensure your car is locked. And every time my car is lock l double check three time after locking it and what is funny is that the alarm installed is not something l activate or deactivate. Do you perhaps know what l can do to stop these annoying false messages or where l can check where the fault is in the alarm system. Your help will be greatly appreciated. I have bookmarked your article for my reference and l will share it with my friend, colleagues and my neighbour his car alarm goes off more than 4 times a day and l wonder what is going on.Great post, by the way l love the way you designed your website it looks amazing.

    • Gabriel G. says:

      Hello Fiona, thanks for stopping by! I am glad you gained some good information from the write up 🙂

      It depends on what type of vehicle you have, but if you are getting a warning like that then I would lean towards it being a failing remote fob, or there is an issue with the receiver module inside the vehicle. If you send me the vehicle info I can look into it for you

  • Christine says:

    I so needed to read this! Car alarms make me nervous, and I freeze when they go off for no reason. Usually, a double click will do to silence the false alarm, but it doesn’t always work that way … And you are suddenly in the spotlight 😉 making all that noise with your car, and everyone is staring … 😉 I would prefer to call a mobile mechanic or locksmith. Are locksmiths also knowledgeable about electronic car keys? Maybe that’s a silly question, but I was just wondering. 

    • Gabriel G. says:

      Great question Christine! Nowadays from what I have seen it seems like most locksmiths are able to work on the alarm/security systems in newer cars. What is very helpful about that is they can usually cut and program a key for you on the spot, which will save hundreds of dollars not having to have it towed to the dealer. 

      Here is a small tip in case your alarm/horn ever goes off and leaves you in the spotlight somewhere: 

      -Learn where your vehicle’s horn fuse or horn connector is located. That way if it ever starts to make noise you can at least quickly silence the horn until the problem is diagnosed and corrected. I know how embarrassing it feels when the horn starts going off and everybody is watching you haha

  • evans says:

    Its already a known fact that car alarms go a long way to help keep our cars safe and secured in our absence cos their could be set to trigger off on it’s own of tampered with…Again at a point one may likely to wanna turn of his alarm totally for best reasons perfectly known to him or her.

    This review is perfectly prepared to give out the knowledge needed to use the car alarm properly and after gone through it will definitely help you..

  • Feji ben says:

    I must say you have a very nice layout and the idea to setup this blog is superb….i have been having issues with car alarm as it would just start ringing out with anyway touch or effect..

    I going to be ordering the diagnosis tool today so i could resolve this issue…i must say this tips you have given would be of help to everyone.

  • David nelson says:

    I must say a very big thanks to you for sharing this awesome article on how o reset a car alarm…although I haven’t had that issue of car alarm issue, you can never know when it could come in handy… I have hard the thought of getting a diagnosis tool but I wondered for what reason and I think this one is a very necessary reason to have one along with the check engine light. Thanks!

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