ASKO Washer Error Code Thermistor

The Thermistor error on an Asko washer means the machine detected a fault with its water temperature sensor during a wash cycle. Specifically on W640 and W660 models, the program ran to completion but skipped the heating phase because the thermistor was either short-circuited or open-circuited. The thermistor is responsible for reporting water temperature to the control board, and when it fails, the machine cannot safely operate the heater.

The washer will continue to run cycles, but all washing will be done in unheated water, which means sanitization programs and hot wash cycles will not function as intended. Fabrics that require hot water to clean properly will not be washed correctly. It is best to address the fault promptly, though there is no immediate safety hazard from using the machine for cold wash cycles in the short term.

If only the wiring harness needs reseating or minor repair, costs may be limited to a service call fee, typically in the range of $75 to $150 depending on your location. If the thermistor itself requires replacement, parts and labor combined generally fall in the range of $100 to $250. Asko is a premium appliance brand and parts pricing can be higher than for more common brands, so obtaining a parts quote before authorizing repair is advisable.

A knowledgeable DIYer can begin by checking all wiring connectors leading to the thermistor for looseness or corrosion, which sometimes resolves the error without replacing parts. Testing the thermistor with a multimeter to check for short circuit or open circuit conditions is the next step. If the sensor reads zero ohms or infinite resistance, replacement is required. Working around the heating circuit does involve electrical components, so disconnect the machine from power before inspecting any wiring.

A power reset may temporarily clear the displayed fault, but the error will return as soon as the machine runs another cycle and the control board again fails to receive a valid temperature signal from the thermistor. The underlying sensor fault must be corrected to permanently clear the code. Resetting without repair only means the next wash load will again be completed without heating.