The thermistor measures less than 4 inches in length. It is located beneath the front panel on front-loading machines. It sits at the bottom of the washing tub next to the heater. On some top-loading machines, the thermistor is built into the main electronic control board behind the control panel.
Other top-loading machines mount the thermistor to the bottom, back side of the machine, on the outer tub. A parts diagram, typically included with repair or owner manuals, indicates the exact location.
The procedure for accessing and replacing a thermistor varies by manufacturer and by machine type. Always make certain that the washing machine's power supply is disconnected and that the water supply is turned off and disconnected before attempting to make any repairs.