Checked the archives but no use... Vehicle goes into limp after around 7 miles and logs 17964 (P1556) Charge pressure control: negative deviation. Performance until this point is very good, we've checked inlet trunking, waste gate (vane control lever) for sticky operation but was OK, I've supplied the system with vacuum and used component activation to watch variable vane being operated by the vacuum actuator all seemed OK. I've watched the boost specified versus actual boost and all is OK until limp mode is activated, checked vacuum level supplied by vac pump 25 in Hg, Checked exhaust for restrictions OK, Replaced charge control solonoid but no difference, VW dealers have said it needs a new turbo, but until this intermittent fault occurs boost is brilliant is that plausible?