Maytag Dishwasher Error Code Thermistor failure

The Thermistor Failure code means the control board detected a problem with the thermistor, the sensor that monitors water temperature during the wash cycle. The fault is indicated by the Delay LED and Heavy Wash LED flashing together during the Field Service Test. The thermistor should read 10K ohms at 77°F and 2.4K ohms at 140°F. A reading outside these values confirms the sensor or its wiring circuit has a problem.

Running the dishwasher with an active thermistor failure is not recommended. Without an accurate temperature reading, the control board cannot properly regulate water heating, which can result in inadequate sanitization, poor wash performance, or the machine stopping partway through a cycle. There is no safety hazard like a fire or flood risk from this specific fault, but continued use will likely produce unsatisfactory results until the sensor is repaired.

Disconnect power to the dishwasher before testing. Locate the thermistor in the wash tub, disconnect its wiring harness, and place your multimeter probes on the thermistor terminals. At room temperature around 77°F, you should read approximately 10K ohms. If the dishwasher was recently run and the tub is warm near 140°F, the reading should drop to approximately 2.4K ohms. A reading of zero, infinite resistance, or a value significantly outside these figures confirms the thermistor has failed and needs replacement.

Start by entering the Field Service Test mode to confirm the code, then use a multimeter to test the thermistor's resistance directly at the component. Compare your reading against the spec values of 10K ohms at 77°F and 2.4K ohms at 140°F. If the thermistor is out of range, replace it. If it reads correctly, inspect the wiring harness and connectors for damage or corrosion. A professional technician is advisable if the wiring and thermistor both test good, since the next step involves diagnosing the control board.

A replacement thermistor is generally an inexpensive part, typically ranging from $15 to $40 depending on the specific Maytag model. If you are comfortable using a multimeter and disconnecting appliance wiring, this is a DIY-friendly repair. If a technician is needed, expect to pay a service call fee plus labor on top of the part cost, which can bring the total to $100 to $200 depending on your area.