Thanks for that.
This is from the service manual
F07: Heater relay stuck or element open circuit
This fault is only signaled when pressure switch is in empty position.
Check the efficiency of edge connector J3 on module.
Check wiring to heater and continuity of element (31 ohms approximately).
Check the efficiency of pressure switch connections and correct operation of pressure switch, and the pressure chamber is not blocked with sludge.
Remove edge connector J3 and check wiring and contacts at positions 2, 3 and 4 on J3.
If all above OK replace pressure switch, module or eeprom as required.
Unplug the appliance.
Take the top off.
Locate the pressure switch.
Take the thin tube off and blow down it.
Give the pressure switch a couple of good taps.
Take the rear panel off.
The board is bottom left when viewed from the rear.
The heater is at the bottom rear of the tub.
Check the heater.
Check the wiring to it.
Take the main board out, check the wiring to the plugs.
Take the plugs off of the board, check the printed circuit board is ok.
Ensure the plugs are clean, dry and tight fitting.
Reassemble the appliance.
Try it again.
If it all checks out ok, it's likely you'll need to have the main board changed and programmed to the appliance.
Please note, new boards are blank. They have to be programmed once fitted to the machine and need special equipment.
Hope this helps