UK Appliance Repair Questions? Ask a Technician for Answers ASAP
If you have replaced the heater and the thermistor and its still not heating then its either the wiring in the door or the main control board.
What you need to do is remove the outer wooden door and then remove the metal outer door panel.
There you will see the wires running down the door to the under side.
You need to release the wires from there and open the loom. Then give each wire a tug and check for broken wires. As the wires can break in there at the bend as they go underneath the dishwasher. Ive found the thermistors wires like to break a lot in there as they are thinner then the heater wires.
But if the wiring in there are fine then it will be the control board itself at fault. As theres a heater relay on there which can fail and it stops the heater from comming on. If this is the case then the control board will need to be replaced from there.
So check them and see what you find. As it will be either the control board or the wiring harness here casuing this fault you have.