The pressure sensor does fail - I've had 2, one on my project car and one on my other half's car. When they fail properly with some form of short, they result in fuse 38 burning out which in turn takes out the power steering controller - on the first this was the case and the sensor broke up when I was trying to remove the connector revealing massive corrosion - and the other half was irreversibly corroded onto the condensor (which I also replaced). On the other one, it was just registering as "Open to (ground or positive, I can't remember), Sporadic", and on this one it was possible to unscrew the old sensor and replace it.
If it fails, the a/c doesn't emit cool air ; I don't remember it simply causing "Econ" to be on all the time.