Cars just ticked onto 101k the other day. Started her up cold and heard this police siren noise as the revs dropped from changing gear. No smoke, no loss of power, and after being ran for 5 minutes it goes away !

Any one know what it is ?

Only thing different has been driving round in this bad weather, hit a few puddles but nothing special

thanks , matt

Means the turbo is run in fine. Do a search, very well documented this last week including posts from someone who had a visit to a turbo specialist because of this noise.

did do a little search but didnt find too much. bit weird how its came around at 101k its original so wud have ran in many moons ago . thanks for the help tho hutchy!

When i say run in.... I mean parts have worn normaly, some say its a sign of turbo failure but other have had it for years... Heres a quote from a day or two ago that might help you.

Just had a diagnostic test on my new turbo by Awesome GTI, as I was worried about this dreaded 'Police Siren' noise. They confirmed nothing is wrong with the turbo

As part of the diagnostic test, they put an endoscope into the turbo and there were no signs of wear, damage or imbalance. That was the news I was hoping for!

They also checked all sensors for readings - all seems okay (no leaks or boost issues). The turbo noise is normal apparently!!

Depends how loud we're talking. If its quite loud and stops once warm I'd guess at the turbo being on its way out. If its quiet then it's just normal noise

barely noticable ive just got a good ear! strange, would expect somthing like this to increase as the temperatures rise and it has to work a little harder .

i'll just keep my ear on it i suppose, keep a 500quid to one side aswel haha

Mine also makes a siren noise when it's cold, it couldn't be classed as loud and it seems to stop fairly quickly once the engines warms up.