ADT Door Sensor Not Working? (How to Troubleshoot)

The ADT door/window sensor works fine. However, you may sometimes experience niggling issues with this smart device. Sounds like you? Keep reading!

In this post, we’ll try to walk you through some troubleshooting steps to help you fix your faulty ADT door sensor. Let’s dive in.

ADT Door Sensor Not Working

If your ADT door sensor isn’t working correctly, here are some reasons for this issue:

  • Low battery power.
  • Damaged/pinched wires.
  • The sensor is malfunctioning—may require power cycling/reset.

Now let’s look at how you can fix this issue.

Tips to Troubleshoot ADT Door Sensor Issues

1. Replace the Battery

If you have a wireless ADT door/window sensor, you should start your troubleshooting by replacing the battery. Low battery power can reduce the sensor’s performance, or even worse—it will stop working—when the batteries are completely drained.

Normally, the ADT system will notify you if the battery in your door sensor needs replacement, but this doesn’t happen all the time—perhaps because of bad battery/incorrect settings.

So regardless of whether you received a low battery notification, replace the battery if the sensor is malfunctioning to see if it resolves the issue.

To replace the battery, you’ll need to get a fresh CR1233 battery or CR2032 battery—depending on your device model. Next, put your system in test mode—to prevent false alarms. Here’s how to do this:

  • Go to and sign in.
  • Click “My Alarm” on the dashboard.
  • Click “System Management” and then click “Place System on Test”. This will put your system in test mode.

Alternatively, you can call 800-ADT-ASAP to put your system in test mode.

You can now replace the battery. Remove the cover by pushing in the tab on the end of the contact—using a flathead screwdriver. Then remove the old battery and insert the new one—following the correct battery polarity (+/-).

Next, replace the cover and ensure you remove the system from test mode. Here’s how to remove the system from test mode:

  • Go to and sign in. Next, tap “My Alarm” on the dashboard.
  • Tap “System Management” and tap on “Stop Test” from the options. This will remove the system from test mode.

Note: After replacing the battery, you may need to reset the security system by entering your code and pressing the “off” button twice.

Your door/window sensor should work fine now. If not, continue to the next step.

2. Inspect the Wiring

For a hardwired door sensor, damaged or pinched wires may cause some issues. If your ADT door sensor is hardwired, try running a check on the wiring and fix any damaged or pinched wires.

Note that it’s best to have an expert handle wiring issues to avoid causing more trouble. So if you have no experience with this, get an expert to check and fix wiring issues.

3. Restart the Sensor

Sometimes, all you need to do to fix a malfunctioning ADT sensor is to restart the device.

So if the problem persists, the next thing you want to do is restart the sensor. Check whether your sensor has a restart button. If so, press and hold it for a few seconds until it reboots. If it doesn’t have a restart/reset button, restart it via the control panel.

Here is how to do that:

Enter your code (on the security system) and hit the off button twice. This will restart the system.

Is your ADT door sensor now working properly? Congratulations. But if not, here are other fixes to try:

  • For a wireless door sensor, check that the cover is properly secured. Not securing the cover correctly may cause some issues (such as the tamper showing the zone faulted).
  • If you’ve recently replaced the door, check that the magnet was attached to the new door properly.
  • More so, the gap between the contact and magnet shouldn’t exceed 1/4 inch. Leaving larger space can cause the point or zone to show “faulted”.

If your ADT door sensor is still not working after trying all the tips, try contacting ADT for help.

Wrapping Up

There may be different reasons behind the problem with your ADT sensor, so you want to try all the tips to see where you’d hit the right spot.

To recap, if your ADT door sensor is not working, start by replacing the battery and ensure you use the correct battery. If that doesn’t help, check for any wiring issues and try restarting the sensor via the control panel.

If everything fails, contact ADT Support for help.

You may also want to see how to troubleshoot/program ADT door lock.