Why Does My Motion Sensor Security Light Keep Flashing On/Off?

Written By Maria
Last Updated June 7, 2021

Motion Sensor Light Keeps Flashing - Why? And How Do I Fix It? Your Questions Are Answered! 

Motion sensor lights are great, aren’t they? 

They alert you to things when there’s movement. Provide a good sense of security. 

Thing is, that all goes out of the window when they stop working properly. It becomes frustrating and certainly doesn’t serve its purpose!

So let’s look at why my motion sensor security light keeps flashing on/off?

The issue could be with the lights themselves, the bulb could be about to go out (this is less likely with an LED bulb but still possible). 

Or it could be an issue with the settings on a motion sensor. 

Want to explore further? 

[By the way, if your sensor light is staying on permanently, rather than flashing, you may want to look here instead!]

An Issue With The Lights On The Motion Sensor

This is quite a likely problem, to be honest. You often find that the sensor is working fine but the bulbs are having problems. 

Why does it happen?

  • A bad bulb. Even the best light bulb eventually have their day. As I mentioned earlier, LED bulbs can go on for a long time but new bulbs can sometimes have issues so don’t immediately rule this out as a possibility, just because it’s a new bulb!
  • The connection between the bulb and the light fitting may be poor and need reconnecting
  • The connections are being obscured by something and only making contact occasionally. This will cause flickering. 
  • A faulty circuit can cause the light to come on and off, this can happen when the sensor hasn’t even been triggered.

All of these problems aren’t related directly to the sensor itself but will need looking into. 

A good first step to take is to change the light bulb. This will rule out a simple cause. 

If that doesn’t resolve the issue, it could be time to call in an electrician. They will be able to take a closer look at the circuit and do some more elimination to determine the issue.

Our list of the top security lights with a motion sensor!

Issues With The Settings On A Motion Sensor Light

The general principle of a motion sensor is the same across the board. 

When the sensor detects a certain level and changes in heat in their vision then it will be triggered. This will switch the light on. 

As we all know, there are a lot of reasons why the sensor might be triggered but sometimes it is to do with the settings.

If they aren’t set correctly, it can cause an issue. 

Your best first step is to reset the sensor and its settings.

  • Whatever the setting is currently set at on the motion sensor, try to put it into ‘test’ mode. A lot of models of sensor lights will have this mode as it is designed for this very purpose! It gives you an opportunity to check the sensor out and if need be, reset it.
  • Take a look and see if the sensor is pointing in the right direction. If you open the sensor up, you may see that the sensor is actually pointing in a different direction to what you thought. If it’s pointing at say, trees, it could be the cause of the problem. If that’s the cause, simply reposition the sensor so it can’t be interfered with.
  • The range of the motion sensor might need to be adjusted. What is quite common is to find that the settings straight out of the box set the range to the maximum. 

What this means for you is that your sensor light could be detecting something which is actually quite far away from your property and therefore not a concern to you. 

Have a play around with the range to find what is best suited to you.

  • Some motion sensor lights will come with a ‘pet immunity’ setting. If you have pets, it’s a good idea to activate this. 

Even if you don’t have pets and the people around you do, it could be worth activating this setting. 

This setting will prevent the light from being triggered when an animal under a certain weight goes into the sensor area. 

Find the right balance so that the light will still be triggered when a human walks into the targeted area but not a pet. It’s a really useful feature! 

  • Have a look at the angle range of the sensor. This is different from the distance range. Each sensor will have an angle where it will operate within. Commonly, this tends to be around 180 - 360 degrees. Having said that, it’s also not uncommon to find motion sensor lights that have a wider angle and this will account for it capturing movement that you don’t want to be captured. A neat way to investigate this to stick two strips of tape on both sides of the sensor. This will narrow the angle from which it can be triggered, allowing you to choose your range. Got it?

When you have done some or all of those things, you can switch your motion sensor light back to active mode.

Hopefully, what you will find is that your light is no longer giving you a disco! 

If you’re wanting to do the opposite and keep your motion sensor light on all the time, you can find out how to do that...here!


I have always had a profound love for reading, which naturally evolved into writing too! This passion for the art of crafting stories using words lead me to a path of web content managing.

I have previously managed portfolios for my clients' writing requirements, with each website containing anywhere from 5 all the way to 5,000 pages; my day was easily filled with spreadsheets and databases of content. My current focus is BestReviews.co.uk where I am the Lead Editor and Content Stategist!
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