Hoover HDPN2D360PW-80 AXI 13 – Main Pump Runs Constantly

Good Evening,

I have a Hoover HDPN2D360PW-80 AXI 13 place dishwasher that has an issue with the main pump running constantly except when the door is open (and obviously when the power is off at the wall). It does however run when the door is closed and the dishwasher is turned off (power supply on).

The drain pump is working correctly and empties the water OK.

9 out of 10 time a cycle will run and complete (pump continues at the end until intervened (door opened or power supply off). Sometimes it display ERROR 18 which in the Hoover app it says this is an issue with water level. If this occurs it is always within the first 5 minutes of the cycle. I have checked the drain pipe is high enough, checked impeller and that the inlet is ok as well as flow is ok. I believe this error is caused because the main pump is pumping when it should not be.
When the error occurs the pump continues to run. The reason I know it is the main pump and not the drain pump is because when you open the door at this point you can see the rotors moving and water being sprayed.

I have tested and also tried a different pressure sensor (the one connected by a small pipe to the side of the sump) but the same issue remains.
I have done the usual check for blockages/broken glass etc in the sump.

I have seen there is a safety pressure switch that looks like it is at the back maybe where the water is heated (part number 41901973) so that is may next thing to check.

Do you know of anything else that I should check that would cause the pump to run like this?

Thank you for your help.
Best Regards

Stephen