2001 Volvo S40 Low Oil Pressure Light

[3blackdots]

Hey guys,
First off thanks for reading this and offering your help
But to get straight to the point first off THE OIL IS NOT LOW. It is full and there are no leaks, car drives perfectly normal and doesn't appear to be anything wrong with it however when my car is idling there is a low oil pressure light that comes on periodically, sometimes blinking on and off randomly and other times staying steadily on. Typically, when I first start the car there is no oil pressure light, but after driving for a couple minutes it will appear and only when idling around 700 rpm at first. Whenever brought above that it goes away but after driving the car for longer typically around 30 minutes it will come on no matter what speed randomly appearing on and off. After even longer around 1+ hours it will come on no matter the speed and steadily and wont go away. Anyone have any idea what could be causing this? The oil was changed about 2k miles ago and I don't know if this is any help but I recently had a CEL at the same time too for a oxygen sensor. Doubt it has anything to do with my oil but thought i'd include it just in case. THANKS!