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Burglar Alarm Not Working
Your burglar alarm will not set, is showing a fault, or is completely unresponsive.
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What's happening?
A burglar alarm that is not working may fail to arm, display a fault code on the panel, or have a completely dead keypad. Intruder alarm systems in the UK range from simple bell-only systems to fully monitored installations. When they stop working, your property is left unprotected.
What usually causes it?
- Backup battery dead or failing — the most common cause of alarm faults
- Sensor fault preventing the system from arming
- Keypad or control panel fault
- Mains power supply to the alarm panel interrupted
- Wiring fault between the panel and a sensor or sounder
- Zone tamper fault caused by a loose sensor cover
Is it dangerous?
A non-working burglar alarm is not an electrical safety risk. However, it does leave your property without security. If the alarm stopped working after a power cut or surge, there may also be damage to the backup battery.
Can I fix it myself?
Check the keypad for error messages or fault codes and consult the manual. Check the mains supply to the alarm panel — it is usually connected via a fused spur near the panel. If the display shows a battery fault, the backup battery needs replacing. Walk around and check all sensors are firmly closed and not hanging off the wall.
When should you call an electrician?
Call an electrician or alarm specialist if the panel shows a fault you cannot clear, if the alarm will not arm despite all sensors looking correct, if the panel is completely dead, or if you need the backup battery replaced (some systems require an engineer to reset after battery replacement).
What will the electrician actually do?
- Inspect the alarm panel for fault codes and diagnose the issue
- Test the mains supply and backup battery
- Check each zone and sensor for faults or tamper conditions
- Replace the backup battery and test the system
- Repair or replace faulty sensors, wiring, or the panel
- Test the sounder and communication links (if monitored)
What will it cost to fix?
£60–£200
Battery replacement is the cheapest fix at around £30-£60 including labour. Sensor or panel replacements will cost more depending on the system.
Find an electricianFrequently asked questions
We’re happy to answer all your questions.
Why is my burglar alarm showing a fault?
The most common reason is a low or dead backup battery. Alarm batteries typically last 3-5 years and the system will flag a fault when the battery drops below a usable level.
Can I replace the alarm battery myself?
On some systems you can, but many panels require an engineer code to clear the fault after replacement. If your system is monitored, your monitoring company may need to be informed.
How often should alarm batteries be replaced?
Backup batteries should be replaced every 3-5 years as preventive maintenance. Sensor batteries in wireless systems typically last 2-3 years.
Should I upgrade my old alarm system?
If your alarm is over 10 years old, modern systems offer better features including smartphone notifications, wireless sensors, and smart home integration. An upgrade may be more cost-effective than repairing an obsolete system.
Sources & References
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