Washer/Drier – Should I replace the main board next?

F13 I think is the dryer thermistor, did you change this one

on some washer dryers failure of the dryer thermistor stops the pump working properly

Dave

also check the wiring to the thermistor has not got a break in it

as for replacing the board, most hotpoint boards have to be programmed after installation

Dave

you need to check the thermistor from the board connection to make sure there are no cable breaks

if it is broken it tends to break on the clips as the cable goes from the drum to the casing

and yes you can buy the board plus you will need to buy a programmer plus you will need to buy the correct software

Dave

if the cable is going to break its right on the wiring clip check this carefully

discolouration is from the heat of the dryer

if you want to be certain trace the cable back to the board and you should be able to read the ntc from there

Dave

I think, and this is a gut feeling (which could be well wrong) that IF the wiring is ok and IF the actual dryer element or wash element are NOT to earth that it would be a pcb fault. Which of the two different elements is your machine fitted with: 1 was a spiral, part number C00080765 and the latter type wasn`t spiral, part number C00268319? Rust deposit on the element, in itself, does not prove it is duff but a matt coloured or rusty swelling or/and a longitudinal split does. = you would also still get a meter reading – element tag to tag but you would to varing degrees also get an earth reading = tag to an earth point e.g. the aluminium alloy heater container so maybe test for that too by putting what meter you have on highest ohms reading and see if the needle or display actually picks something up – you would need a 500 volt producing dc megger rather than an ordinary test meter but you might get lucky wioth whatever you have to prove the point. Testing the machine with the heater wires removed and taped to insulate will just throw up another error code. There was years ago a new version of the thermistor you recently bought = part number C00290251 because the original gave grief but they do look very slightly different when compared to each other.
So as a rough guess, all that above being well, I think it is probably a switching relay on the pcboard. What, if you are lucky, are looking for is a duff relay leg soldering joint which would be obvious and with a soldering iron/ solder DIY fixable. BUT if unlucky it could be anything on the board such are the evils and joys of electronics.Take a photo befor moving off any wiring connectors.
PCB changing for customers and trade bods without the manufacturers tools. As someone touched on already you would have to buy at great expense a new pcb. You would also have to buy a smart card and a smart card reader The pcb is based on your exact model and its industrial and serial code too so cannot tell you how much if you went down that route but = lots. The smart arse card is about 25 quid and the card reader about 190 quid ! i.e. they have customers caught by the short ones when out of the X number of years free parts warranty early stuff 5 years latter stuff 10 years.