Folger Tech 2020 I3 Error Mintemp

Just before my 3d printer is about to print, I get an error on my LCD panel stating; Err Mintemp. This is after the heat up process of both the heat bed and the hot end but before the actual printing process. The error shows up right after my print head moves to the starting position for my first print which is a 10 mm cube. However, after the error shows up, the print head continues to "print" the actual cube without the extruder motor engaging. I know for the newest version of repetier which is my host program/slicer that if a mintemp error is found then it won't engage the extruder motor. I've check all over the internet for solutions and did most of them, from reconnecting the connector, measuring the resistance, checking the wiring, and measuring the voltage. The only anomaly I found during my diagnostics is the voltage which was a bit too low; approx 4 volts. I don't know if this is bad or not but my knowledge in 3d printing isn't that great. I know the thermosistor is working up to the point before the starting position as the temperature is registering properly from the LCD screen. But after that it drops back down to zero and give me the error. I'm still new to 3D printing and this is my first 3D printer I've built. So what to do now?

did you check if the thermistor is firmly attach to the heat block, also the thermistors comes with Folger Tech aren't really good, at least mine weren't, everyday I get mintemp error because it reads below 5c no matter the room temperature, I replaced both my thermistors with Semitec 100k Ohm NTC, and I have had no problem ever since, matter of what, my Folger Tech isn't much of a Folger Tech anymore other then the 2 stepper motors I'm still using that is from them, other parts either don't work properly or burned itself out on their preprogrammed firmware.