Problem with temperature readings

[killerpig 0]

I haven't used my printer in a while but recently tried to and I'm getting constant maxtemp errors when preheating the nozzle. It goes up at a steady rate of about 2-3 degrees per second until it reaches around 170deg, then it starts jumping up by 10 degrees per second until it gets a max temp error.

 

Does anyone know a possible cause of this problem? Is the temperature sensor defective?

[gr5 2,224]

This used to be a common way for temp sensors to fail although lately I haven't seen a bad temp sensor in over a year (I have tested hundreds).

 

You can't use solder in a temp sensor because it will melt (the old lead solder melts around 250C and lead free solder melts around 200C so neither are useful).  So instead the wires are crimped to the temp sensor.  When you heat it up metal expands and if the crimp isn't tight enough the resistance suddenly starts increasing (which makes it look like the temperature increased even though it didn't).

 

Anyway you need a new temp sensor.  shop3d.ca sells them in canada.  I sell them in usa.