A tamper error occurs when the panel is reading that the sensor's cover is not attached properly. To address the tamper error on your TX-E721 motion detector, follow the instructions below.
1. Open the cover by pressing the tab at the bottom of the sensor.
2. Ensure the battery is correctly installed and that there are no loose springs or obstructions preventing the motion detector from fitting snugly with the backplate.
3. The tamper switch will be pressed by the backplate if the sensor is closed correctly. This will ensure the condition is resolved.
You will also need to clear the error from the panel memory by following these instructions: How to Clear Alerts on the IQ Panel 2.