Why Does My SimpliSafe Entry Sensor Show Open When the Door Is Closed?
- Magnet shifted too far from sensor on door frame
- Sensor adhesive loosened allowing sensor to move
- Low battery causing intermittent sensor communication
Problem Description
Your SimpliSafe entry sensor reports the door or window as open when it is actually physically closed. The SimpliSafe app shows the sensor as open and the base station may chime or trigger an alarm when the system is armed. This creates constant false alarms and prevents you from arming the system in Away mode because it thinks a door is open. The issue is typically caused by sensor magnet misalignment low battery or a sensor that has shifted from its mounting position.
Symptoms
- App shows entry sensor as open when door is closed
- Base station chimes open door warning constantly
- Cannot arm system in Away mode due to open sensor
- Sensor status flips between open and closed randomly
- Alarm triggers immediately after arming in Away mode
- Sensor worked fine for months then started misreporting
Recognize these? Here's what usually causes it.
Common Causes
- Magnet shifted too far from sensor on door frame
- Sensor adhesive loosened allowing sensor to move
- Low battery causing intermittent sensor communication
- Door has warped or settled creating larger gap
- Sensor mounted on metal surface interfering with magnet
- Magnet installed with wrong polarity facing sensor
Most fixes happen in the first 3 steps.
Do not ignore a sensor that constantly shows open. If you bypass the sensor to arm the system that door or window will not be monitored and an intruder entering through it will not trigger the alarm. Fix the sensor rather than bypassing it.
Tools & Requirements
These tools will help you complete this fix.
Level
9 Inch Torpedo Level Magnetic, Shock-Proof Small Lev...
Replacement batteries
Energizer Ultimate Lithium AA Batteries, Long Lastin...
Isopropyl alcohol
ForPro Professional Collection 99% Isopropyl Alcohol...
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Step-by-Step Solution
Check Magnet Alignment
The entry sensor has two parts. The larger sensor piece mounts on the door frame and the smaller magnet piece mounts on the door itself. When the door is closed these two pieces must be within half an inch of each other and aligned side by side. Check if either piece has shifted. Door vibrations from daily use can gradually move adhesive-mounted sensors. Reposition so the pieces are directly adjacent when the door is fully closed.
Replace Battery
Low battery causes the sensor to send incorrect or intermittent status reports. Open the sensor housing by sliding or prying the cover. Replace the battery. Gen 3 sensors use a CR2032 coin cell. Check the SimpliSafe app under Devices to see the reported battery level. If it shows low or if the sensor has been installed for over 3 years replace the battery regardless of the reported level as the sensor may not accurately report its own battery status.
Needed for this step
9 Inch Torpedo Level Magnetic, Shock-Proof Smal...
$6.99Clean and Remount
Remove both sensor pieces from their mounting location. Clean the mounting surfaces with rubbing alcohol to remove old adhesive residue. Apply fresh double-sided mounting tape or use the included adhesive strips from a new sensor pack. Press firmly and hold for 30 seconds. The mounting surface must be clean and dry for the adhesive to hold. Avoid mounting on textured or dusty surfaces.
Needed for this step
ForPro Professional Collection 99% Isopropyl Al...
$11.99Test the Sensor
After repositioning open and close the door slowly while watching the SimpliSafe app. The status should change from open to closed within 1 to 2 seconds of the door reaching the fully closed position. If it still shows open with the door closed try flipping the magnet piece around as some magnets have a specific orientation that must face the sensor. Also try moving the magnet slightly closer.
Re-Pair with Base Station
If the sensor still misbehaves remove it from the system and re-add it. In the SimpliSafe app go to Devices find the sensor and delete it. Then go to Add Device and follow the prompts to pair the sensor again. This clears any corrupted pairing data. After re-pairing test the door open and closed states to confirm accurate reporting.
Quick Solutions
Still having issues? This is usually the deeper cause below.
If this comes back after following these steps, check whether a recent app or firmware update reset a default setting — the fix works, but the setting gets reverted silently.
For doors with large gaps between the frame and door surface use the included sensor spacer or stack two pieces of mounting tape to bring the magnet closer to the sensor. Even a quarter inch improvement in gap distance can fix detection accuracy. **Product Intelligence:** - CR-2032 battery (2-3yr) - Magnet gap: up to 1 inch
Battery-related failures are almost always flagged too late — the device degrades silently for days before the app catches up to what's actually happening.
- Magnet shifted too far from sensor on door frame
- Sensor adhesive loosened allowing sensor to move
- Low battery causing intermittent sensor communication
- Door has warped or settled creating larger gap
- Sensor mounted on metal surface interfering with magnet
Before you go — try one of these (they fix most cases).
Most popular upgrades chosen by SimpliSafe Entry Sensor owners.
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Official Manufacturer Manual
SimpliSafe provides official product documentation through their online manual rather than downloadable PDF. Access setup guides, troubleshooting steps, and product specifications for your SimpliSafe Entry Sensor.
Source: simplisafe.com
Need More Help? SimpliSafe Support
Note: The contact information below connects you directly to SimpliSafe's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.
How Does SimpliSafe Compare?
Before replacing your SimpliSafe device, see how it stacks up against alternatives in our full comparison guides.
