yellow oil light on 2001 BMW 325i

My yellow oil light just came on, what does this mean>

Asked by for the 2001 BMW 325i
Yellow: incorrect oil level
Red: incorrect oil pressure
These cars have problems with the thermal oil level sensor, so if the oil level is correct, take your car to a BMW specialty shop for further diagnostics. It requires OE diagnostic tool, so most repair shop won't be able to do it