oil level sensor malfunction
Same problem here but surprisingly only after i washed my motor. I live up in Quebec, Canada and decided to wash off all the salt that was entering the engine compartment and voila the minute i drove it out of the garage it came on with that warning.
After driving for a few days it finally disappeared.
Now it is back and you can see why just by looking outside, the roads are sloppy and wet, slush splashing everywhere. It's been on for about two days and finally has returned to normal. I am assuming with enough driving that the engine heat dries out the moisture and corrects the problem.
I have a 2011 28i and 18,000kms.