The oil pressure sensor light flickers when I slow down or come to a stop. I've been told1) the sensor needs to be replaced and/or 2) I need to use a heavier wt oil because my oil pumps is getting weaker. I have about 400 miles left on my current oil change.
If there is no knocking or ticking when the light flickers, chances are the oil sending unit is bad. It isn't an expensive part, under 20 bucks. Replace that and see if it fixes the problem. If you DO hear a knocking or ticking from the engine, then you need to check pressure with a mechanical pump and maybe even replace the oil pump.