Like lots of us here,had the those heart stopping moments with this going off!; esp. when was just setting off for tour of France on hols!
Basically, didn't want to got through this again so just fitted an oil pressure VDO gauge, sender from a VW coup (sorry,can't remember more details, but got it off ebay, S/h £21), now at least know exactly what's going on back there at the engine and no false alarms!
All best with things though
Cheers.