Biomass 40 - Controller issue

Biomass 40. RK-2001 controller runs has been acting up. It will run fine with no wood burning.
As soon as the boiler is burning and gets up to about 170 the display starts tripping 8s across the display. Sometimes it clicks every second as the 8s dance across the screen. Now it is followed by E-1 which per the manual means the temp sensor is damaged due to temp over 300. I can't think of when or how it got over 300 as I have a 500 gallon storage tank.

Anyway, questions:

1. Controller is under warranty. Do you think it is the controller?
2. Do you think it is the boiler temp sensor? I tend to think so but with the crazy 8s I can't be sure.

Anyone experience this before or have advice. Thanks.

It should be under warranty.

Sounds like it could be the capacitor though

http://www.hearth.com/talk/threads/...ler-flicker-flashing-blinking-e2-code.104233/

So much for my theory that vents on the side of the controller housing makes biomass boilers immune from controller problems!