If a DOOR Smart Home Sensor shows offline, won't trigger, or triggers when it shouldn't, the cause is almost always one of three things: the batteries, the DOOR Hub, or where the sensor is placed. Because every sensor reports through the Hub, a sensor that "stopped working" is often a Hub that went offline.
Before you start — who can check what. Residents see only the devices assigned to their own unit. The Hub is normally assigned at the building level, so checking whether the Hub is online is something only a property manager can do. If you're a resident and a sensor has stopped working, do the battery and placement checks you can do yourself, and if those don't fix it, contact your property manager — they can confirm the Hub's status and escalate to DOOR Support if needed. The Hub checks below are for property managers and installers.
Symptom
A sensor shows Offline in the DOOR App, doesn't report events, reports false events, or its battery drains quickly.
Quick fix
- Check the batteries. A fast red LED blink every 30 seconds — or a low battery level in the app — means the batteries need replacing (2 AAA for most sensors, 2 AA lithium for the Temperature and Humidity Sensor).
- Are all your sensors offline at once? That usually points to the Hub. Property managers/installers: open the DOOR App and check whether the Hub is online — if it's offline, fix the Hub first (see DOOR Hub troubleshooting) and every sensor should come back. Residents: you normally can't see the Hub (it's at the building level), so contact your property manager to confirm its status.
- Confirm range (one sensor only). If just one sensor is offline while others are fine, it may be beyond the Hub's wireless range. Move it closer; if that helps, a property manager can add a Hub to extend coverage.
Possible root causes
- Hub offline — the sensor can't report without the Hub, so it appears offline even though it has power.
- Low or dead batteries — the most common cause of a sensor dropping off or missing events.
- Out of wireless range — a single distant sensor can't reach the Hub.
- Placement problem — for the Open and Close Monitor, too large a gap or a loose door causes false "open" readings; for the Motion Detector, heat sources or direct airflow cause false motion; for the Leak Detector/Lasso, the electrodes or rope aren't where water actually collects.
- Alert turned off or not configured — the sensor is fine, but the relevant alert isn't enabled in its Settings.
- Cold temperatures — battery capacity drops in the cold; AAA-powered sensors are rated to 32 °F for optimal battery performance (the Motion Detector supports lithium AAA down to −4 °F).
Step-by-step diagnosis
- Check whether all sensors or just one are affected. All offline → the Hub is the likely cause. Checking the Hub requires building-level access, so this is a property-manager/installer step; if you're a resident, contact your property manager to have the Hub checked. One sensor offline → continue with that sensor (the steps below are things a resident can do).
- Check the battery — replace if the LED blinks fast red every 30 seconds or the app shows low battery. Confirm the batteries are seated correctly and are the right type.
- Power-cycle the sensor — open the housing, remove and reinsert a battery, and watch for the LED to blink red then green (powered on, reconnecting).
- Confirm range — move the sensor closer to the Hub temporarily and see if it comes online. If it does, it was out of range; reposition it or add a Hub.
- Address false triggers by sensor:
- Open and Close Monitor reads open when closed — the gap is too wide or the door has play; move the magnet closer (within ¾"), and off the hinge side.
- Motion Detector triggers with no one there — move it away from HVAC vents, heaters, and sunny windows; lower the height or re-aim it.
- Leak Detector/Lasso false alert — confirm the electrodes/rope are dry and not bridged by a wet surface or condensation.
- Confirm alerts are enabled — open the sensor's Settings and verify the alert (and threshold/interval) is set, and that the DOOR App has notification permission on the phone.
When to escalate
Residents: escalate to your property manager first — they confirm the Hub is online and contact DOOR Support on your behalf.
Property managers/installers: contact support@door.com if:
- A sensor stays offline after fresh batteries, a confirmed-online Hub, and a move closer to the Hub.
- A sensor reports events that never match reality after placement has been corrected.
- The status LED stays solid or blinks in a pattern that doesn't match power-on, normal operation, or low battery.
Include the property name, the Unit, the sensor type and serial number (in the DOOR App under the sensor's settings), and what you've already tried.
Related articles
- Operating your DOOR Smart Home Sensors
- DOOR Smart Home Sensors overview
- DOOR Hub troubleshooting
- I can't see my Smart Home devices in the DOOR App