Just unplug it. (blue plug, back right side of inlent manifold) Very unscientific test, but i found that unplugging it when it's already dead/dying on the cinq had no negative effect and the exhaust smelt a bit "fuelly" as it did with it on. When i replaced it the cars exhaust instantly didn't smell so rich, felt sharper on the throttle etc, then when i unplugged for a test it knowing it was now fine, the car misfired briefly and went back to smelling like it had a fuel leak, plugging it back in almost instantly smoothed out everything. Seem to remember my idle dropped a good bit too with a good sensor.
Basically if it has no effect when you unplug and reconnect, it's needing changed.
Fwiw, i'd be tempted to just stick the whole inlet/tb etc from Fiasco on it given the coolant sensor is on the inlet and we're not too sure if theres any issue with the TB, either injector wise, flow wise or icv wise. but for the sake of unplugging one sensor, it's worth a wee look.