). They can check to see if there is one as I mentioned, but they can actually cause issues if they are applied unnecessarily - as other components / software may also need updating - which they may not be able to be,- depending on hardware and software versions. They are quite tightly managed for this reason and won't apply an update (if indeed there is one) for this reason unless it is required.I've seen cases, myself included, where a BSI update has had a knock-on effect to other systems.
But going back to that specific fault, it can be the condition of the oil:-
It's more to do with the particle filter. It's the regeneration element that causes the issues where the engine oil gets diluted by the diesel fuel. A resonant sensor system for determination of diesel content by measuring the viscosity of the oil can be used - and this is the issue being referenced by the fault as far as I can see.
Diesel fuel that contains the particle filter additive floods the cylinders - and gets past the piston rings into the engine sump. So where this is detected as being too diluted - it can flag the fault code and that is why one of the remedies is to change the engine oil.