We can replace a new sensor to you, but in order to avoid new sensor failing to work, there are some simple ways to identify sensor problem:

1. If the senosr installation position is right? Please make sure you put the sensors paralell and less than 1 inch. (the close the better).Sometimes the sensor will move slightly as not attached .

2. If the device red connector part is right? If you disconnect the sensor wire, the device is in door open status. Please try to short the two pins in red connector, if the door shows closed in app, then device is right. If not, please contact us for device replacement.

3. If the sensor wire is right? If you move the magnet sensor close and away from the wired sensor, no status change. Then we suspect the sensor wire is broken.

If you confirmed the sensor defect, please contact https://meross.com/support/Email_Support for sensor replacement.