Before attempting to change the thermistor, check the low fuel indicator circuit and the associated indicator light in the gauge cluster is in working condition.
To check this circuit, take a small piece of wire and attach pin 3 (with Green/Red wire) either with the car body or directly with pin 1 (with Black/White wire) to ground it temporarily and see if the "low fuel" indicator light comes on or not.
The condition of fuel gauge sending unit shows that the fuel tank requires a cleaning job.