The Malfunction trouble condition indicates a device is unable to properly communicate.

If a Z-Wave thermostat is in malfunction, try the following steps to resolve the behavior. 

1. Verify the device is powered on.
2. Verify the device is within range of the Z-Wave network. 
3. Power off the device, if possible. Wait a couple minutes, and then power the device back on. 
4. Trigger the thermostat by manually changing the temperature on it. 
5. If the device is still in malfunction, contact your service provider.