Why Does My Alarm Keep Going Off For No Reason?

False alarms are never convenient, and can even cost you money if the police respond to your home too many times. Here are some common causes of false alarms in a security system and what you can do to fix them.

Quick answer

How to troubleshoot and fix false alarms

Let’s explore the list above to find out more about common false alarms in security systems like those from SimpliSafe. We’ll also explain how to identify the cause of your false alarm and how to fix it.

Pets trigger motion sensors

What to look for

Watch your pets as they roam the house. Be sure to note if they walk through an area with a motion detector. Next, get your pet to go through that area while the alarm is armed (or in test mode). If an alarm goes off, you’ve found the problem.

How to fix it

Check with the company that sold you the motion sensor (or check the manual) to see if it’s “pet-immune.” If it’s pet-immune, you can ask the company how to adjust the sensitivity, otherwise you might have trouble with the next step.

Check with the company that sold you the motion sensor (or check the manual) to see if it’s “pet-immune.”

Adjusting the sensitivity depends on the brand. With some you need to open the sensor and flip a small switch or move a jumper elsewhere on the circuit board (be sure to disarm your alarm system first). With others, you mount the motion sensor upside-down to have it point away from the floor.

If the motion detector isn’t pet-immune, you’ll need to replace it with a motion sensor that can work with pets your system.

Heaters trigger motion sensors

What to look for

If there’s no alarm from your pet (or you don’t have a pet), check to see if there’s a heater below your motion sensor or an air vent that blows on it. If so, try turning on the heater to see if the alarm triggers.

Almost all motion detectors use passive infrared (PIR) technology to detect movement through temperature changes in a room. If a heater interferes with this process, it can cause a false alarm.

>>Learn more: How do motion sensors work?

How to fix it

Move the motion detector or heater to a different location so the heat won’t affect the sensor.

Dead batteries or faulty equipment

What to look for

Many sensors have a small LED light that turns on when they detect something. Try activating the sensor by moving it. You can also open the case (this can set off a tamper alarm in many systems). If the LED doesn’t turn on, it’s either a dead battery or a defective sensor.

How to fix it

Put a new battery in the sensor. If it starts working again and doesn’t trigger an alarm, you’re done. If the house alarm keeps going off or the sensor doesn’t work, replace it with a new sensor. If the sensor is under warranty, you can likely get a free replacement from the manufacturer.

Improper installation or programming

What to look for

If you installed your security system yourself, be sure to check the installation manual to see if you missed any steps. You can also examine the sensors and equipment to see if they got damaged during the install.

If a professional installed your security system, do a quick visual inspection for damage to the devices or call customer support for help.

How to fix it

If you caused damage to the system, you won’t be able to get replacement equipment using the warranty—you’ll need to buy new equipment.

If you think the professional installer made a mistake, you can get help by scheduling a service appointment (as long as the installer offers a warranty on your devices). Sometimes another installer can fix the problem as well.

>>Learn more: Security Sensor Installation: Tips and Tricks

User error

What to look for

Check to make sure you know all of the correct keycodes for disarming your system.

Make sure you can disarm the system quickly enough when you get home, or that you have enough time to leave after arming. There’s often an exit/entry delay that gives you time to control the system without triggering an alarm.

How to fix it

If you forgot your code, you may need to reset the alarm system (or have a technician do it) to put in new codes.

If you can’t get to the panel fast enough to disarm the system, adjust the entry delay so you have more time. If arming the system, change the exit delay.


You don’t have to put up with security system false alarms. Most of the causes are easy to fix so you can feel more secure.

If you don’t have a security system yet, consider taking a look at our review of the best home security systems.