I had three 9x0...it is a bloody fecking issue with these bikes
First my 950 ADV 04. One day it started out of the blue. Topped up oil and so on. No results. To cut the story short after few thousand kms the filter got completely blooked and the noise and light was constant. There were debris of metal into it. The fron cylinder was gone. Changed under warrenty. Bike went very well for a long time. But one day it did it again. And than once again. Just randomly. Why? I am not sure.
Anyway what I woukld suggest are the following:
Do full oil change. Change the oil filter and check the magnetic bold that is in the lower side of the oil tank. Check if is there any debris that might have cloth the filter (obstructed). Make also sure you run the bike with the reccomanded oil. Than if it stll does it...take it to a good garage.
they reccomand highflow oil filter to sort this problem. I have never tried!
With the two following 990 I never had the light coming up but I had the rattle noise indeed! It is usually as soon as you start it. Sometimes yes...sometimes no. Why? Good knows.
The only thing I got to understand is that the rattle, eventually followed by the light, is due to a lack of oil passing throgh the system.
The causes can be various.
Start from the esier one: oil filter. Debris obstructing the filter. Oil pump.