SimpliSafe Sensor Not Responding — Fix Guide

What it means

SimpliSafe sensor not responding means it has lost communication with the base station.
Replace the battery first — a dead CR2032 or AA battery is the most common cause.
Then test the sensor in the SimpliSafe app.

How to Fix It

Replace the sensor battery

Open the sensor by pressing the release tab or sliding the back cover.
SimpliSafe entry sensors use a CR2032 3V lithium battery.
Motion sensors may use AA or CR123A batteries.
Insert a fresh battery with correct polarity.
Test the sensor after battery replacement

In the SimpliSafe app or on the keypad, enter Test Mode.
Open the door or window with the sensor, or walk in front of the motion sensor.
The base station should announce the sensor name.
Check the sensor is within range

SimpliSafe uses a 433 MHz radio for sensor communication.
Thick walls, metal objects, and large appliances reduce range.
Keep entry sensors within 30 metres (100 feet) of the base station with as few walls as possible.
Re-add the sensor to the SimpliSafe system

Using the keypad: enter your Master PIN, go to Settings > My System > Devices and select the problem sensor to remove it.
Then re-add the sensor following the device pairing instructions.
This establishes a fresh radio link.
Ensure the base station is not obstructed

Place the base station in a central location, not inside a metal cabinet or near large metal appliances.
Metal obstructions significantly reduce the range of SimpliSafe radio signals.
Contact SimpliSafe support for hardware failure

If the sensor fails to respond after battery replacement and re-pairing, the sensor hardware has failed.
Contact SimpliSafe support for a replacement sensor — sensors are covered under the product warranty.

Frequently Asked Questions

SimpliSafe sensor worked for months and suddenly stopped responding — why?

The battery has most likely drained.
SimpliSafe sensors can last 3–5 years on a battery, but lithium batteries can fail suddenly at end of life.
Replace the battery first.

SimpliSafe sensor says not responding but I can see it detecting movement — is the app wrong?

This can happen if the sensor is in a different mode or has a weak radio link.
Try triggering the sensor during a keypad test to confirm — the keypad will announce whether it receives the signal.

Multiple SimpliSafe sensors not responding at the same time — what is wrong?

Multiple simultaneous failures point to the base station rather than individual sensors.
Check the base station is powered on and that the app shows the system as connected.
Restart the base station.