ERR: No Temp
Maybe some of us have seen it. For me, I was cleaning out my print head after a disastrous print. The PLA pushed against the Thermistor wires, breaking them causing the I3 to not receive any temperature readings from the print head. Don't worry, we've all been there.
Most likely, the error is being caused by a broken or damaged thermistor, the module your Ender I3 uses to monitor temperature inside your heating mechanism. If you take this apart (its pretty easy to do so, really user friendly) you will find a ribbed metal tube with a piece of brass on the bottom with a set of white wires. Trace these wires into the side of the brass piece. If the wires are severed, odds are you won't get the thermistor head out. DON'T WORRY. I HAVE A FIX FOR THIS. Above the thermistor port, you will find a screw designated for holding the thermistor head in. Order a new thermistor (link below). Take this screw out and discard or keep at your choice. Into the threaded hole, insert your new thermistor head and secure with something like solder (be careful not to melt the wire insulation. The wire on the thermistors is temperature rated. I needed to use a propane torch to strip the wire just to give you an idea).
You also might notice that the thermistor wires are hard to track into the back of the printer. If you're engineering skills are keen, there is a shortcut around this. You will need some shrink wrap or another insulator. Locate the end of the old thermistor wires and snip them. Use something like a lighter to melt the insulation off the wire as the insulation is decently strong. Snip the ends of the new thermistor wire (close to the other exposed set of wires, be logical) and attach the wires, insulate as needed. Once reassembled, your printer should be good to go.
Link to replacement thermistors:
Save time and aggravation replace your thermistor with this and never worry about snapping it again. I've had a few mishaps and they clean right off no problem. :) https://gulfcoast-robotics.com/products/2017-version-hex-screw-in-m3-epcos-thermistor-for-3d-printer-extruder-hotend