I had this problem on my Ecobubble washer dryer over the past week. The thermostat switch on top is connected to the Heater Element housing (hence error 'HE2' - Heater Element 2).
When it pops it means the housing has gotten too hot. This can happen because of several reasons:
1. Blockage preventing air flow / causing lack of air leading to over heating.
2. Fan not functioning - hence lack of air flow and over heating.
3. The water inlet valve to the lint catcher is not working (I could hear this was working on dryer cycles before the failure occurs so not too concerned about this). This could lead to a lint build up and air flow blockage.
I took apart the heater element housing (metal and black part on the top) which reveals the lint catcher on the back of the machine. This comes out very easily. It's mounted with two screws on the back. Work your way around and you'll see it's easy to disassemble.
I found that the fan sending hot air around the machine from bottom to top was clogged with lint. I removed it all with an old toothbrush and a small screwdriver.
Next, I took apart the lint catcher at the back of the machine. Simply pushing all the lint out is dangerous because it could get clogged elsewhere. Best to remove it and clean it.
Once the lint catcher was out I cleaned it out thoroughly and then replaced everything.
Remember to reset the thermostat switch and whilst you're at the back of the machine, get a torch and look for frayed, loose wiring towards the bottom of the drum. Mine was all OK.
Finally, open the front 'lint' catcher and clean that out. I found stickers, bits of lint, hair, string in there but it's not as effective as cleaning out the big catcher on the back of the machine.
My machine is three years old so I'm not surprised there was such a big build up of lint in the machine. I'll be cleaning this out more regularly now.
I agree with some of the comments here - don't just blindly reset the thermostat switch hoping it'll fix your problem (even some you tube vids show this). That is very foolish and you're asking for trouble.
If the thermostat switch trips then it has tripped for a good reason and you should investigate further before you have more serious problems i.e. fire hazard!!
I hope this helps someone out there!! :)
Jaimin, February 2018