Since yesterday, I'll face exactly the same issue. I check the oil level, add some (now, the gauge is upper the max graduation), check the oil filter housing (nothing missing or gone - plastic guide/springs) and... the light still come on, as soon as the car runs under 2000rpms !!!
Did you find something ? I think I will replace the pressure sensor... (but half hearted... since it's just a contact with a ball and a spring)
Let me know please, if you find something. Cheers (and good luck ;-)