Thank you Daox,
I seem I recall that I've read somewhere that the post cat sensor output is evaluated by the ECU of some models (e.g.
http://www.audiworld.com/tech/eng53.shtml) , but I don't know if it is the case with the Honda.
Anyway while my LTFT is always negative, STFT varies. But perhaps I miss something. If LTFT is negative I understand the ECU should try to compensate by injecting more fuel. Yet it seems the sensor doesn't sense the added fuel...
But perhaps it's too late and I should go and sleep...
Stefano