Engine bay fan always on

Hi,

Last month I was working on my TF, which I acquired a few months ago and noticed that the plug to the engine bay cooling fan was disconnected. So I plugged it in and I immediately found out why it was disconnected: the fan comes on when I turn the key and doesn’t shut down until I turn the engine off. So now I am tempted to disconnect the plug again, but at the same time I just want it to work properly. Has anyone any suggestion on what to do? Thanks

IIRC the ECU controls the fan based on feed pack from a sensor close to the header tank on later cars.
If this fan is treated the same as the front radiator fan the ECU will run it if it doesn't see a reading from the sensor.

It occurs to me that somebody may have disconnected the fan because it ran all of the time.  This would very likely be due to a sensor fault.  If I remember correctly, Normally, with the ignition on, the engine bay fan runs if the sensor is disconnected.