07 S8 Red oil light

Ok, my son’s S8 has started showing the Red oil symbol and does not allow the car to start. This has happened 2 twice now and this morning he was going to work and the car would not start and the red oil ligjt came on. Always the car runs excellent, especially after the intake manifold change out.

My questions are ( no codes, oil level is great )

Oil pressure switch?
Oil presure Sensor?
Anything else?

Thanks