The dishwasher needs to be unplugged and the thermistor disconnected. Use a multimeter to measure resistance through the thermistor. The room temperature is 75 degrees. The thermistor should be replaced if the meter is less than 1,000 ohms or more than 20,000. If the thermistor resistance is good, connect the wires to the thermistor and check resistance through the thermistor wires that connect to the electronic control board. The thermistor's resistance should be read the same by the meter. If the electronic control board is not accurate in detecting thermistor resistance, you'll need to replace it. If the meter has infinite resistance or less through the sensor wires, you can find and fix the thermistor wiring failure.
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