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Hello everyone,
It's the first time I write in this forum.
My brother and I have an '85 chipped URquattro, a 91 chipped V8 quattro 3.6 and since yesterday a RS4 2.7.
Today I scanned the car with the VAG-COM and I found this problem:

17965 - Charge Pressure Control: Positive Deviation
P1557 - 35-00 - -

What does it mean? The car works great and seems to be in good working order. No warning lamp on the dash.
Any suggestion?
Thanks in advance
Nicola - Modena
ITALY

Welcome to the forum.

OK this could be caused by either the turbo boost pressure being too high or the deviation between requested and actual boost being too great.

as you have Vag-com, try logging block 115 under full throttle in 4th gear. the factory manual suggests that the boost specification at 3000 RPM should be between 1.870 and 1.980 bar. Also there should only be a max deviation of 20 mbar between requested and actual boost. If there are any differences then this could be due to boost leaks.

Hope this helps, and let us know how you get on.

I would suspect the DV's, sounds like as posted above the requested boost and actual boost is different. Pull the control hoses off the DV's and suck on the nipple!! If it holds vacuum its OK, if it doesnt then bin it and replace with '710N' type.

need to do a pressure test, sounds like you have a hose problem..
cheers
jr

Thanks for you advice. I've a MityVac suction pump. This week (If I've spare time) I'll try to test the Waste Gates, the Dump Valves and the TBB.
I'll let you know.