By removing the four screws on the top part of the door and tilting the control panel down to remove it, you will see a black wire that is connected to a thermostat that should be clipped onto the inner metal panel (down and to the right) replace it in its clip and secure it with a zip tie. If this doesnt cure the problem then you will need to check the heater element because its probably blown it due to overheating, last but not least, if the element is in good condition then its got to be the PCB (part number for the Indesit IDL40UK is C00142139 approx £50) that is on the panel you removed to replace the thermostat. It is possible to repair the PCB and the fault is probably the 12v 10a relay and if your confident enough can be obtained from Maplins who do 2 possible replcements with thi same footprint (numbers JM67X and YX97F approx £2). I gleened this information from a number of sources and I thank them for it all, This as far as I can tell is all it can be and its nothing to do with no salt or rinse aid, and my machine is back up and running. I hope this helps others that have lights 2 & 4 flashing and want an answer.
hippytitimus
March 2010