Taz 5 Dual Extruder 3 Issue

I have a Taz 5 with the Dual Extruder V3 head. Prior to now the head had been working flawlessly on either extruder or both.

It sat for around 4 months unused (terrible, I know!) and now gives me a ‘E1 heating failed’ error when I try to get it set up for a print. I usually use the right extruder for single color/material prints. It will get most of the way up to temp and then fail. Seems to happen just past 200C. The left extruder seems to be ok, getting up to temp and holding it well. I try to reserve this nozzle for flexible/dissolvable materials.

I am running he 1.1.5.71 firmware, cura 2.6.69, but using Octoprint. My head appears to be one made just after the thermistor problem SN KT-CP0127-0494, so I wonder maybe it slipped?

What causes this error?

My bet would be on the thermistor crimp. Try squeezing each pin with pliers as an immediate fix. Best to just replace the thermistor… its pretty simple to perform the swap.

Well, now I’m frustrated. Crimped the leads to the E1 thermistor, and now the printer goes straight to E0 MINTEMP error and resets. Recrimped the E0 thermistor to no avail. One of it’s leads was very loose and it came apart almost immediately.

Is the MINTEMP error mean it can’t see the thermistor at all now?

Lulzbot help!!

I have a 6 and if any connections expected at boot are not there, it will halt with a related error, so probably. Time to break out a multimeter. FWIW, I was one of the early V3 dual thermistor connection failure victims last year, I resolved it by soldering all the thermistor related connectors on the print head end and never looked back.

This part says it does not fit the V3 dual, but it is physically very similar in construction to the dual’s sensors:
https://www.lulzbot.com/store/parts/100k-semitec-ntc-thermistor-235mm

The salient points are that it should be ~100K ohms @ ~room temperature and look at all six crimps related to each sensor out towards the print head.

Update: I got a new v3 dual yesterday and the connections for the thermistors are now soldered from the factory.