Temp sensor defect error

Hey everyone,
I recently purchased a Prusa i3 Reprap 3D printer but the extruder and hot bed don't seem to heat up during printing. My extruder motor works fine but it just doesn't heat up. It seems also as if it is not able to read the actual temperature of the hot bed and extruder because instead of reading a temperature it just days "def".
I downloaded Repetier and connected it to my printer where it gave me this in the log:

extruder 0: temp sensor defect
heated bed: temp sensor defect
Errorrinter set to dry run mode until restart!

Any help would be awesome as I have tried to contact the seller several times and when he finally gets back to me he is of no help.
Thanks!

Edited 1 time(s). Last edit at 05/26/2016 04:58PM by 808brick.

Check the connections to the board, be sure are plugged to the right pins, ask the vendor the type of thermistor you have and check in the firmware that the type is correct.

Haven't seen that error message before.

Ok so i have fixed the problem. I checked for continuity throughout the wires of the thermistors by using tiny pins and my voltmeter and I found that the crimps on the end of the wire where the it plugs into the circuit board is were bad. Fixed this by taking the wire out of the plug, re-stripping it, then putting on a bit of sawter before reapplying the crimped piece and put it back into the plug. After this I began receiving temperature reading and was able to print.

Nice work, and thanks for letting us know.

I'm having this same issue, will try your technique and hope it works!

this is a thermistor problem most likely a break in the wires going to the board an ohmmeter test on plug ends should show a resistance reading infinity indicates a bad wire or broken thermistor usually under the heavy insulation near the bead . wires can be fixed crushed bead needs replacing.

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rwt