Hoover DDY 088T dishwasher error code E8.

Hi.

I hope someone can help. As above, the washer sometimes has error code E8. Manual says “heater element not working correctly or panel filter needs cleaning’. I replaced the element with a genuine spare part having metered the old one which proved faulty (suspected it anyway as water didn’t get hot on a quick wash).
Put on a 70Deg wash and it worked flawlessly. Typically when I’m on nights and the Mrs puts it on it stops near the end of cycle and beeps with the E8 code again. I have noticed though, that when I put it on I tend to click the extra heat for drying button too. Again, sometimes this works and other times it doesn’t. I’m not sure what or where the panel filter is as there is no mention in the manual.
Another thing I’m surprised at is the time it takes for a wash cycle. Most cycles are over 2 hours long, is this correct? Our old AEG washer was all over in around 45 mins even on a hot wash.
Again, I’ve noticed that at around 50 mins left whist the outside feels really warm if I open the door there is still some water in the bottom of the washer. Later on as the cycle continues, I can hear this water draining.

Sorry for rambling, but I’m trying to include as much as I can about this fault!
Thanks in advance.