i would get it checked straight away, the official line from bmw is that this problem was fixed in 04 onwards plate diesels however i know a bmw mechanic and he says the defect will affect all models upto the new shape release of 2005 models, my failure started with a thin whisp of smoke from the back and the turbo got louder and louder for around 3months until BANG!!! inside a tunnel smoke blocking the vision of other motorists and choking them, this caused a multi car pile up and lead to a road closure until the car was recovered NOT GOOD BMW GET IT SORTED!!! the repair cost to my car is £850 for a reconditioned turbo (i was very lucky the main turbo bolt didnt enter the engine if this happened i would be looking at a £8k bill) it blew doin 30mph in rush hour.