RDC8 I have pulled out the autofill probe and it looks like it might be damaged. There is a rough edge to the tip, as if something has broken off, and the probe is dry when removed. There is water in the boiler as I have also removed the safety valve and inserted a bamboo skewer - it comes out wet.
They are cut to length, it’s not damaged and a fall would not have broken anything of the top of the probe.
The first check to make to begin to isolate the fault:
Unplug machine….Take the autofill prob wire, and definitely ground it against the boiler or chassis.
Ideally, If you have a multimeter, check there is continuity from the earth pin on the plug to outside the boiler, or use a 1.5v battery, wires and a bulb…then
Plug in machine and if pump continues to run, switch it off and check for;
- Defective or loose wire from probe to Autofill control box
- Defective earth
- Defective control box