Fan always on + STOP light on dashboard

[arooscroocked]

Hey, since Christmas I haven't had time to take care of it properly, but I think the easiest thing I can do is changing dashboard temperature sensor (the blue one).

The thing that bother me the most is how temperature gauge moves depending on driving situations - when I'm driving in heavy traffic (centre of Warsaw) temperature rises to 90* and above sometimes, but doesn't exceed 100/105* - I feel that fans kicks in properly. But then just drive a few hundred meters in mixed conditions and temperature falls to 80-90*. Higher speeds outside the city? Below 80*.
For me it's too... repeatable? I would be tempted to believe that it should be so, because indication of the gauge seems so logic (higher speed - better cooling, traffic jam - high temp), but I also believe that indications shouldn't "fluctuate" so much.

First thing I would think about would be thermostat but I changed it already.
Blue dashboard sensor? Actually last thing that left to check, even if it doesn't looks like it's faulty. Guess I'll replace this sensor within few days (paycheck incoming) and let you know if it solve the problem.

God, I wish I've had thermometer that covers this range of temperatures to check them in more "analog" way bypassing the sensors.

Stay tuned!