Hello

My 2008 8v 1.9CDTI has taken to making a whining / whirring noise. It becomes more pronounced when the engine is revved, and is present regardless of whether or not the car is in gear. It's been doing it for a few weeks, but I had hoped the oil change and service done a few days ago would have fixed it, but no.

It sounds exactly like this:

Performance doesn't appear to be affected, and there is no obvious smoke, aside from an occasional puff when starting in really cold weather.

I've had a look round, and possible causes are the DPF (which I thought cleaned itself on motorways etc - I do around 300 miles a week on these), the alternator, various belts. The

Can anyone advise on what it is, and how to fix? I'm thinking that it is probably an idler pulley (after reading this thread) - but my car has a slightly different engine.

What would happen if I don't get it fixed?

Thanks in advance