When an ADT door and window sensor goes offline or shows a trouble or supervisory fault on the panel, the sensor has stopped reporting, which usually means a weak battery, a lost signal or a damaged sensor. Wireless sensors check in with the panel at intervals, and if the panel hears nothing for a set time it reports the sensor as missing, and may beep. IGotC's guide on beeping ADT sensors lists the usual causes: a low battery, interference or distance from the panel, and a sensor that has been moved.
The checks in more detail
Start with the battery: replace it with a fresh one, following the sensor's instructions. Then check the case is closed and the sensor is within range of the panel, with no metal objects or large appliances between them; a sensor on a metal door frame, or behind a refrigerator, may lose signal. SafeWise's guide notes that the gap between sensor and magnet should be under about a quarter of an inch, and that a sensor mounted off alignment may report incorrectly.
Move the sensor nearer the panel to test: if it reports well there, range is the issue and a repeater or a different position helps. Check whether other sensors are offline, which points to the panel or to interference, such as a new router or cordless phone near the panel. If the whole system is affected, restart the panel by following the manual and, if it is still wrong, ask the installer.
A sensor that was working and then went offline after you painted the frame or fitted a new door may have been disturbed or covered with metal flashing. If the sensor will not report even with a new battery and a close position, delete it from the panel and enrol it again, or replace it. Keep a note of which sensors fail and when, since a pattern points to the cause, and have the installer check the panel's wireless receiver if several fail.
Differential
Likely causes of “ADT Door/Window Sensor is offline or unavailable”, and how to tell them apart
- 1
A weak battery
What separates it The sensor drops out or beeps
How to confirm Replace it
- 2
Distance or metal
What separates it The signal does not reach the panel
How to confirm Move the sensor or add a repeater
- 3
A moved or misaligned sensor
What separates it It reports wrongly
How to confirm Realign it with the magnet
- 4
Interference near the panel
What separates it Several sensors drop
How to confirm Move the panel's neighbors or ask the installer
- 5
A sensor that needs enrolling again
What separates it It is not recognized
How to confirm Delete and enrol it again
Before you touch a setting
Record this first — changing settings destroys the evidence
- Which sensors are offline
- Their battery age
- Their distance from the panel
- What changed recently
Try in this order
0 of 6 completedReplace the battery
ReversibleFresh, right way round.
Close the case
ReversibleAnd check alignment with the magnet.
Test near the panel
ReversibleTo check range.
Check other sensors
ReversibleFor a pattern.
Delete and enrol again
ReversibleIf it is not recognized.
Ask the installer
ReversibleIf several fail.
Model-specific
What is true of this model and not of its siblings
- Supervision
- The panel expects regular check-ins.
- Metal
- It can block wireless signals.
Stop boundary
When this stops being a self-service repair
- !If several sensors drop, ask the installer to check the panel's receiver
- !If a new battery and a close position fail, replace the sensor
- !Tell the monitoring company
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Why is my door sensor offline?+
A weak battery or lost signal.
Can metal block the signal?+
Yes.
Why do several sensors drop?+
The panel or interference.
Should I replace the sensor?+
If a new battery does not help.