Are you sure the level is fine? Switching off and finding the yellow light on is normally a warning that the level is a bit low. Check oil with the engine still hot (10 mins after shut off).
Mine was the same, I was convinced the level was fine, as soon as I topped it up everything is fine again.
The other possibility is the oil level sender in the sump, which can easily be replaced but is not particularly cheap.
Red oil light is oil pressure related.