Short answer
The cause of a false alarm is often not the device itself; a sensor fitted in the wrong place, a weak battery, a loose door contact, an insect inside the sensor or user error triggers the alarm. The first step in finding the cause is to look at the panel's event log and see which zone triggered the alarm. If the same zone goes off again and again, the problem is in that sensor or around it.
Look at the event log first
At every alarm the panel records which zone was triggered and at what time. A zone is each sensor the panel identifies separately. You can reach this log from the keypad menu or from the phone app. Replacing sensors on a guess without opening the log wastes both money and time.
Look at three things in the log: which zone, what time and how often. If the same zone always goes off, the problem is in that sensor or its placement. If different zones go off at random, there may be a problem with the panel, the power supply or the wireless communication. If alarms always come in the afternoon, the sun or the air conditioner should come to mind.
The log can be overwritten over older records or may keep only a limited number of events. So when you have a false alarm, check the log the same day and write down its date, time and zone name somewhere. Going to the service with these notes speeds up finding the problem.
Causes 1 and 2: sensor location and heat sources
A motion sensor detects the movement of a heat difference. If a radiator, an air conditioner outlet, a fireplace or a window that gets afternoon sun comes into its field of view, it can mistake a hot air current for movement. In Şanlıurfa in the summer months, an air conditioner running for long periods and switching off, and sun coming through west-facing windows, are common sources of this kind of alarm.
A curtain swaying in the wind, a balloon hanging from the ceiling, a fan with blades and the airflow from an open window create the same effect. The fix is mostly to change the sensor's angle or move it to another wall. Lowering the sensitivity should not be the first remedy; the sensor may then miss a real burglar too.
When the home layout changes, the surroundings of the sensor change too. A newly bought oil radiator, an aquarium moved into the living room or a tall potted plant placed in front of the sensor can make a sensor that worked fine for months unstable. If the alarms started after the home layout changed, that change is the first place to look.
Causes 3 and 4: loose contact and weak battery
A magnetic contact works by its two parts staying close together while the door is closed. Over time the door sags, the window sash flexes, the tape loosens. When the distance between the two parts grows, a door that moves slightly in the wind can set off the alarm. Tightening the contact's screws or realigning the part often solves the problem. If the door has sagged, the hinge should be adjusted first.
In wireless systems, a sensor whose battery is getting weak can send an irregular signal. Good panels report a weak battery with a separate warning, but when this warning is ignored the sensor starts to behave unstably. If the problem stops after you change the battery, the cause has been found.
Expert note: Plan to change the batteries of wireless sensors at the same time. If one has run out, the others fitted the same day are near the end too. Changing them one by one means dealing with battery warnings for months.
- Find the triggering zone in the event log
- Is the sensor looking at a heat source?
- Are a curtain, balloon or fan in its view?
- Is the door contact aligned and tight?
- Are the wireless sensor batteries strong?
- Is there an insect or dust inside the sensor?
- Is a pet entering the area?
- Is the entry delay long enough?
Cause 5: insects, spiders and dust
A small insect crawling on or inside the sensor lens can look like a large movement because it is so close to the sensor. Spiders like to spin webs inside the sensor housing. These alarms usually come at night, after the lights go off, and always from the same sensor.
Opening the sensor's cover, cleaning the inside with a soft brush and sealing the cable entry hole is enough. In Şanlıurfa, after dust storms the lenses of outdoor sensors are covered in dust; this both impairs detection and raises the risk of false alarms. During maintenance, the lenses are wiped with a dry cloth.
Cause 6: pets
An ordinary motion sensor cannot tell a cat or dog from a burglar. If there is an animal at home, either a pet-immune sensor is chosen, or the sensor of the room where the animal roams is switched off with partial arming. Even with a pet-immune sensor, cats that climb high can trigger the alarm. We cover this subject in detail in a separate article.
A pet's habits at home can change over time. A kitten grows up and starts climbing onto the bookcase, the dog moves its bed to another room. If a system that worked fine for years suddenly starts giving alarms at midnight, first think about whether the animal has started going somewhere new. If there is a new animal at home, tell your installer; the sensor plan may need to be reviewed.
Cause 7: user error and settings
The cause we meet most often on site is the people using the system. Someone entering the house does not know the code, the entry delay is too short, the cleaner forgot the system was armed. These alarms have no technical fix; users need to know the system.
A few settings on the panel reduce these mistakes. The following should be discussed at installation and changed later if needed.
- Set the entry and exit delay according to the time it takes to walk from the door to the keypad.
- Give every person who lives at home or visits regularly a separate user code.
- Have the keypad give an audible warning during the exit delay.
- Define partial arming mode so that only the doors and windows stay armed at night.
- For a wrong code attempt, set a short warning period instead of the siren right away.
When should you call the service?
If the event log shows no particular pattern, if several zones are triggered at the same time, or if the panel gives an alarm on its own after a power cut, the problem is not on the user side. In that case the cable connections, the panel's power supply, the backup battery and the wireless signal strength must be measured and checked. In wired systems, a cable that has taken in moisture or been damaged can be the cause of this kind of random alarm.
A false alarm does not only disturb the neighbors. After a few false alarms, families stop arming the system, and in a real incident the alarm is off. During maintenance visits, Desa Bilişim reads the event log with you, finds the problem zone and fixes the sensor on site. For systems with remote access, the first check can also be done with remote support.
Frequently asked
The alarm went off at night when nobody was there. What should I do?
First think of your own safety; if you suspect someone may be inside, call the police without entering the house. If the situation is safe, look in the panel's event log to see which zone was triggered and check the area around that sensor.
Is lowering the sensor's sensitivity a solution?
Usually not. Lowering the sensitivity can reduce false alarms but increases the risk of missing real movement. Correcting the sensor's position and angle first is the better way.
Why does the alarm go off when the power goes out and comes back?
If the backup battery is weak or there is a problem with the panel's power connection, a voltage fluctuation can produce an alarm. The battery needs to be tested and the power connections checked.
Is your alarm going off for nothing?
Reach us through the quote wizard or by phone, and we will go through the event log together and fix the problem sensor on site.
