Why Does My Car Alarm Keep Going Off at Night?

Updated: Oct. 17, 2022

Car alarm interrupting your sleep? We've rounded up some causes and solutions for why your car alarm keeps going off at night.

Isn’t it annoying when you’re snuggled in for the night and your car alarm goes off?

At first, you worry someone is messing with your car, so you jump up to check on it. After a few nights of false alarms, though, you learn to keep your key fob on your nightstand and don’t even check. Those false alarms defeat the purpose of having a car security system in the first place.

Let’s find out why this is happening and what you can do about it.

Why Does My Car Alarm Randomly Go Off at Night?

Your car alarm is supposed to scare away anyone who tries to tamper with your vehicle. If your car alarm keeps going off at night and there’s no evidence of anyone tampering with your car, what’s going on?

Typically, when a car alarm goes off randomly only at night, it’s one of these probable causes:

The enemy

Have you made anyone mad? Someone may be setting off the alarm just to bug you and interrupt your sleep. Shaking the car, bumping it with a hip or lifting the door handle may be enough to set off the alarm without leaving any evidence behind.

The low battery

A low battery can set off your alarm. If you use your car all day the battery may get low at night, making the alarm sound.

The night critters

Nocturnal animals like cats and raccoons may be using your car as a late-night perch or napping spot. When the alarm goes off, the critter skedaddles, leaving no trace.

The trash truck

Some car alarm sensors are sensitive enough to trip when a large vehicle rumbles by. If your park your car on the street and the alarm sounds around the time the trash truck makes its rounds, you can bet the truck is setting off your alarm.

How To Fix a Car Alarm That Keeps Going Off at Night

Determining the cause of the nighttime alarms will take a little detective work. Set up an inexpensive security camera to watch your car and check the footage the next day. Then, take action.

The enemy fix

If the cause is vengeful person up to no good, show the footage to your local authorities. They can guide you in your next steps.

The nocturnal critter and big truck fix

If the trash truck or late-night critters are setting it off, start parking your car in a garage at night. If you don’t have one, check into renting a garage space nearby, or we can help you DIY a garage. If park outside can’t be avoided, try these tips for getting rid of pesky raccoons and stray cats.

Another possibility: Adjust the sensitivity of your alarm sensors. The process can vary by brand, so consult your car alarm owner’s manual for instructions.

The low battery fix

If there’s nothing on the footage, your car probably has a low battery. AutoZone and most other auto parts stores will test your battery for free. You can also test the battery yourself. If the battery isn’t holding a charge like it should, buy a new one and replace the one that’s causing the nighttime false alarms.