Whirlpool Washer Error Code F66

The F66 code indicates that the steam temperature sensor, an NTC thermistor, is reporting a value outside the valid range of 14°F to 230°F (-10°C to 110°C). This code only appears during a Diagnostic Test cycle. Because the sensor reading is invalid, the washer skips the water heating step during normal wash cycles. The fault typically points to a defective sensor, a loose connector, or a wiring issue between the sensor and the control board.

The washer will continue to run with the F66 fault present, but it will skip the water heating step, meaning cycles that depend on warm or hot water will not perform as intended. There is no immediate safety hazard from the fault itself, but continuing to run the machine without addressing the underlying sensor problem could result in consistently poor wash results. Addressing the fault promptly is recommended.

Repair costs depend on the faulty component. A replacement NTC temperature sensor typically costs in the range of $15 to $50 for the part alone, making it one of the more affordable repairs if the sensor is the only issue. If the control board has failed, parts and labor costs can range from $150 to $350 or more depending on the model and service rates in your area. Checking the wiring and connectors first costs nothing beyond your time and may resolve the fault without any parts.

Some causes of F66 are DIY-friendly, particularly reconnecting a loose wiring connector or cleaning corroded terminals. Always unplug the washer before inspecting any components. If the sensor itself has failed, replacing an NTC thermistor is a straightforward repair for someone comfortable working with appliance wiring, but you will need to confirm the correct replacement part for your specific model.

Unplugging the washer and restoring power may temporarily clear the fault from the display, but if the underlying sensor or wiring problem is still present, the F66 code will return the next time a Diagnostic Test is run. A reset does not repair the sensor or correct a wiring fault. Proper diagnosis and repair of the temperature sensor circuit is required for a lasting fix.