[Familyman 90]

If the car has a full Volvo history theres a tiny chance Volvo may contribute, but not terribly likely. Doesn't hurt to ask.

If it doesnt have full VSH it won't ever qualify for good will. No manufacturer will show good will to customers who have no shown them any.

Unless its an utter lump of coal in there they can usually be easily cleaned, so I wouldn't commit to a new one until the old one has actually been removed and examined. If it hasn't been removed and examined then your garage are only guessing.

Avoid any temptation to remove or disable it. Its a criminal offence - not simply a moving traffic offence or a con & use offence - that carries big fines and the risk of the car being seized and a conviction against your name. It's also an MOT failure, although unless its glaringly obvious the typical tester will have no way of knowing.

To avoid a recurrence avoid using diesel cars regularly for journeys under 7 miles.