Check your oil filter, it may be clogged.
It's also possible that something is obstructing the oil flow somewhere after the oil presure sensor.
Finaly, the oil presure sensor may be faulty.
It may be an harmless situation that may correct itself after some time, but may also be very serious: The oil can't go to where it's needed, causing excessive wear and may eventualy destroy the engine.
Bring your car to a mechanic to check for any problem.
Electro
June 2014