From a post I made a while ago - - -
Oil state.
Flashing or steady red plus three beeps: low oil pressure.
Steady amber: low oil level. Stop and top up. Opening the bonnet resets the oil level trip.
Flashing amber + beeps: oil level indicator fault
Any oil state warning is serious, ranging from "slow down now, stop and top up the oil at the next layby" to "Your sump's just fallen off, kiss your bearings goodbye"
gazbrum: You have the "oil level indicator fault" warning, which means that (as you suspected) the sensor is duff. The oil pressure warning will still activate the red indication plus beeps for low oil pressure, it just won't be quite as noticable with the amber light already on.
The oil level/temperature sensor is in the bottom of the sump.
There's this funny little stick thing that pokes down into the sump and can tell you exactly how much oil you need to put in and whether it's full or not. It is important to have the right amount. Too much oil will get splashed everywhere, and get into the engine intake through the breather, damaging the cat. Drastic overfilling will kill the engine. Use the Dipstick!
Phillc: Any red oil indication needs immediate attention. Wilful neglect of the engine's clear cry for
help will not be covered by any warranty and is likely to cause ribald amusement in garage personnel while they replace your engine. Low oil pressure is serious.
The oil pressure sensor is in the side of the oil filter bracket. Try cleaning the connector first, if the fault is intermittant.