TAZ 5 MINTEMP error but nozzle is fine

My bed wasn’t heating so I turned of and on again, no luck.
I updated the firmware (Marlin, no luck, and now all I get is a MINTEMP error.
Prior to reset and firmware update the nozzle was heating fine.
What can I do to get rid of this error?

Min temp error usually indicates the thermistor is done or the connection to it is broken

it should give a reading of ambient temp at idle when not called to heat anything

you say nozzle is ok, is it still ok if you try to get that to heat on its own? - no error message…

if its just for the bed, you may need to do a little wiring fault finding to see if wiring is broken, or replace the bed heater mat

Initially the nozzle heated normally but the bed didn’t. That’s why I say the nozzle is fine. I didn’t touch the nozzle, I only updated the firmware and then I got the error message. Both the bed and the nozzle read zero degrees and I can’t get either to accept any instructions to heat.

forgive my ignorance here.

have you touched any wiring from the control box?

would be odd (but could happen) that both thermistors are gone. is that the latest Taz 5 firmware you can get? i have a Taz 6 and official Lulzbot is on 1.9. something.

alternatively you could search for Drunken Octopus firmware which is an alternative to Lulzbot FW but is running Marlin 2.0, you will find it on github and via Patreon. maybe try re uploading FW to see if there is a bug in the one you are running. its a free way to test if issues go, all it takes is a bit of your time.

OK, updated to newer Marlin. Still showing MINTEMP error and says, “Please reset”. I’ve turned it off an on again (a few times) but still getting the error. Is there another way to reset?

A power-off resets the printer. So clearly you have a hardware problem.

What’s the full message you get? That’ll tell you if it’s the nozzle or the bed that’s got the problem. Once you figure that out, you’ll need to examine the wiring from the control box to that specific thermister – that’s the most probable issue. It could be a thermister that’s bad, but based on other posts on this forum, that’s highly unlikely to be the issue - far more likely it’s a bad connector or broken wire. Note that the wires do a lot of flexing so a break is likely to be inside the insulation with no outside indication of damage. A multimeter to test the wiring is often helpful.

Where should we be looking for a new hot end thermistor? I dont see anything compatible on the website. Is the 24v heater cartridge (https://www.lulzbot.com/store/parts/24v-30w-heater-cartridge) the right one for this machine? Thanks all for the help?