+1. If you're careful you can move it away from the belt to see if the noise stops. Best use something other than fingers though

 

I'll nip out and give it a go within the next hour. That would be a nice simple fix!

 

Yep, it was indeed the belt sensor - noise stops as soon as I move it away.

Fortunately(?) I already have a new part on order for the turbo from Porsch-Apart which won't be sent out by them until Monday. I'll see if they've got a used 964 belt sensor they can chuck in the package at the same time.

 

Great, its sounds kind of cheap too!!

Another one to add to the memory bank of possible issues.

 

That's good news Dave and credit should go to Newsboy for beating me to the suggestion

I think they're about 60 quid for a new one.