Check cat5 cable.
There is a Cat 5 cable that goes from the Control Panel up to the Header Tank.
Make sure the control unit is powered off.
Check to ensure that both connections are secure.
Use a soft dry cloth to wipe the connectors to make sure there are no particles on the connectors.
Power up the control panel.
![control panel cat 5](https://rainhub.co.uk/wp-content/uploads/2020/04/control-panel-cat-5-300x276.jpg)
![header tank cat5](https://rainhub.co.uk/wp-content/uploads/2020/04/header-tank-cat5-300x252.jpg)
Did this fix the problem?