How a Dishwasher NTC thermistor Sensor works & how to test it

by / Sunday, 14 December 2014 / Published in Dishwasher


Dishwasher Electrical Parts

The temperature is controlled by the PCB by means of a NTC thermistor temperature sensor incorporated in the heating element when you test it the Resistance drops as the temperature rises.

What is an NTC Sensor?

NTC sensor

Dishwasher NTC thermistor Sensor

A thermistor is essentially a resistor that changes its electrical resistance at varying temperatures. The name is derived from a mix of thermal and resistor. They are used in Dishwasher because their electrical resistance at various temperatures is known, it’s easy for the Dishwasher to monitor a thermistor and detect when certain temperatures are reached.

Check all connections first to the Dishwasher sensor and to the board they may have come loose, you are sometimes unlikely to see anything physically wrong but there might be a bad connection. Diagnosis is done by measuring the resistance with a continuity (or multi) meter. We can’t give readings for all thermistors because they vary, see my picture for an example, but you should be able to get a reading across both terminals. If it’s completely open circuit it’s likely to be faulty.

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4 Responses to “How a Dishwasher NTC thermistor Sensor works & how to test it”

  1. Sergey says : Reply

    Thank you, it is helpfull

  2. jens says : Reply

    Hallo, i need your help, i have a ariston ll64 dishwasher and i need to know where is the termistor ntc position, thanks for your answer and help!

  3. John says : Reply

    I have a Indesit dishwasher Model IDL605.It has had a start up problem Number 2 light comes on, you can here the pump draining then water entering, then it stops and number 1 and 3 light starts flashing and nothing happens, You can turn off power leave for a while then start up, and it goes through same motions. I have replaces pressure switch, have pulled pump out and no restrictions. Have looked at main board cant see any burn marks and all connections are tight. If any ideas I would appreciate Regards
    John Emms.

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