Maytag Dishwasher Error Code Heavy Wash LED + Clean LED

This LED combination indicates that the dishwasher's control board has detected a thermistor failure during the Field Service Test. The thermistor is the temperature sensor that monitors water temperature throughout the wash cycle. The fault means the control board is receiving an invalid or out-of-range resistance signal from the sensor or its circuit. The correct thermistor resistance at 77°F is 10KΩ with a tolerance of plus or minus 3%.

The thermistor fault is not an immediate safety hazard, but running the dishwasher with a failed temperature sensor is not recommended. Without accurate temperature feedback, the control board cannot properly regulate water heating, which may result in poor cleaning performance, inadequate sanitization, or improper drying. It is best to diagnose and resolve the fault before resuming normal use.

A power reset may temporarily clear the displayed fault, but if the thermistor or its circuit has a real electrical problem, the error will return once the control board runs its diagnostics again. Clearing the fault without addressing the underlying cause will not restore proper temperature sensing. The correct approach is to test the thermistor resistance and wiring, then make any necessary repairs before clearing the code.

Start by running the Field Service Test to confirm the thermistor fault is active. Then disconnect the thermistor and use a multimeter to measure its resistance at room temperature, comparing it to the 10KΩ ±3% specification. If the reading is out of range, open, or shorted, replace the thermistor. If the sensor tests correctly, inspect the wiring harness and connectors for damage or corrosion before considering control board replacement.

If only the thermistor requires replacement, the part typically costs in the range of $15 to $50 depending on the specific model. If professional labor is needed, total repair costs including parts and service fees generally range from $100 to $200. A wiring harness repair is usually less expensive than a control board replacement, which can range from $150 to $350 or more for parts alone.