I have a Rancilio Epoca E1. Since I obtained it, it has been working wonderfully. Yesterday, My wife fired up the machine, and it was sitting for about two before I woke up. I was standing in front of the machine, and flushed the group head. As I did that, the boiler safety valve popped. That also tripped the GFI outlet.

Curious, I opened the water valve, and possibly 1L maybe less of water came out before only steam. I was suspecting the auto fill sensor was malfunctioning. After letting the machine cool for a few hours, I re-powered the machine (no heat, motor and electronics only). The motor ran for a quite awhile (re-filling the boiler) and I figured all was well so far. I flipped the switch for the heater and waited.

The anti siphon valve rattled and then closed up like normal, and the boiler pressure was rising. I had previously set the pressure stat for ~1.2bar. The boiler kept climbing. I turned off the heat and fetched my multimeter. I clamped on the heater source, and flipped the switch for the element. As the heater was doing it's thing, I waited for the machine to get back up to 1 bar, and tweaked the pressure stat adjustment until the supply voltage for the element turned off. I opened the water and steam valve to drop the pressure, to test the new setting. I let a lot of water out, but the motor never ran to start the refill.

I flipped the heat switch, fearing exposed elements, as i let the boiler drain. The motor finally kicked on and started filling the boiler, and then it stopped. then started, then stopped. Started and then stopped. and again for 2 more cycles. Each on-off cycle was about 1 second or less.

I let the machine cool and removed the level sensor. Nice shiny metal, no noticeable scale or anything.

I need help figuring this one out. At the moment, the machine is behaving, with exception to the motor on/off cycling as the boiler re-fill is finally tripped.

i would suspect the control board if the autofill is acting up. that explains the over fill and the boiler pop, but not the gfci trip. Thats assuming these are like most newer rancilios and autofill is part of the main board.

however espresso parts lists an autofill box for the epoca electronics. does yours have this?
http://www.espressoparts.com/R_234