Extruder temp reading 262-266 constantly

What’s most concerning is its still reading (mostly) 266 even with the hotend thermistor unplugged from the breakout board, as well as the large black ribbon cable (connection E) unplugged from the main board… So it isn’t a breakout board or thermistor issue.

I did recently add a BL Touch, but from research pin 12 of connection E/break out board runs to PF1 (pin 96/temp_pin) and mainboard conductor that runs between the chip and ribbon cable pins are on the other side of the board. My multimeter says the connection between the two is still good, but I realize that doesn’t rule out an issue somewhere, but I doubt I did anything to it while soldering the pins into the EXT connector area.

PS - the hot end won’t heat since it thinks its already pushing/ed its max temp

I’ve got a rotten feeling the mainboard is soup, but figured I’d reach out for any suggestions to try before dropping ~ $115 for a new one…

Without anything plugged, it should be near -15 so yes probably a problem with your mainboard

Gotcha… I kinda figured since when I had a broken wire on a print bed therm it displayed bed temp of -15, and normally when hotend therm is unplugged it would show as -15 as well. So when it wasn’t showing negative, I didn’t have a good feeling about it. Thanks!