Hi All  I've got a 2003 Tdi ASV and it keeps coming up with P1557 charge pressure deviation, I've got the Mr Muscle on standby to do the vane cleaning, but today I decided to replace the vacuum pipes as some looked frayed, when I removed the pipe to the actuator on the turbo I found this.

 

 

It doesn't look like anything that it left the factory with ?? it looks more like something you'd use on a fish tank to control the airflow to the aeration bubblers, it was screwed down so as to restrict any flow through it, after fitting the new pipes I used my vacuum pump for brake bleeding to see if the actuator moved Ok it does move but only about 4mm is this correct ?? on a quick trip around the block it seemed a lot livelier, I'll take it for a better blast tomorrow and see if the code returns.

4mm sounds a little short to me,     I guess that is fitted to restrict the vac flow (most likely )in order to try to (mistakenly?)   limit over boost problems------however it may be there to alter the boost curve --wouldn't be the first       was it metal or plastic and if so near the turbo?

Yes it looks like a small plastic needle valve botched in by a previous owner. I think it should move 4mm, did you try moving it by hand to see if you could force it any further?

It's a plastic item, it was hidden under the engine cover

 

I tried to get my hand down to move the actuator rod but i couldn't reach it (I'm a short A*se) I will try from underneath or if I remove the inlet pipe from the turbo I might be able to get at it ??

Well that didn't cure it !! took it for a run Saturday morning, just over 3K and the power dropped off & got home same code set, so it looks like it'll be the Mr Muscle cleaner trick ??