About 5 times I’ve been preheating my bullet to 250 or up to 275 C and I just letting it run a little while in the PH. Trying to get 20 mins of heat built up, when all of a sudden, without touching the machine, my computer, or anything around it, I hear it says ‘Roasting has Started’… and it goes into the roasting mode. What the heck?!
I had a problem with my bean probe that seemed to be causing this, but I also had a lot of noise on the bean probe RoR graph that first indicated the bean probe problem. A replacement probe fixed this issue for me.
I’ve seen others have the problem due to too strong of an exhaust fan, air blowing back into the exhaust when not using a fan, opening the tryer or door, and sometimes when removing the bean chute plug.
If it just happened once I wouldn’t be too concerned about it. If it is consistently happening you can start checking the other things that could be causing this.
If you’re using Overlay mode, try keeping it off during preheat and activating it just before adding beans. Thanks to @andrewcoecoffee, that tip fixed this problem for me. Hope it’s as simple for you too.