I would suspect that your oil pump is malfunctioning and not supplying enough pressure.
A flash light
The oil light is an "oil pressure" indicator. it means you have lost oil pressure or the oil pressure sensor is bad
Check your oil and make sure there is some there. Actually it could be low oil pressure from lack of oil or from a bad oil pump
2003 cadillac cts has the oil pressure light on
Oil pressure lights are not reset. You need to find out why the oil pressure light is on. Normally this means you have low oil pressure.
If the oil light is working and is off with engine running, then you have oil pressure. To determine how much pressure, you need a pressure Gage.
Oil light senses oil pressure not oil level
an oil light is designed to come on when there is NO oil pressure or LITTLE oil pressure. that said, when your oil light is on before you start your engine there is NO oil pressure to turn it off until you start the engine.
It does not have a reset. If the oil light is on, the sensor has failed or the oil pressure is too low.It does not have a reset. If the oil light is on, the sensor has failed or the oil pressure is too low.
Low oil pressure or failed oil pressure switch.Low oil pressure or failed oil pressure switch.
If you are referring to the oil light then you do not reset it. The oil light comes on when it detects low oil pressure. The light will go out when the problem is corrected. Can be the engine is low of oil, does not have sufficient pressure, or the oil pressure sending unit it bad.