Just now, wulfrunian said:

I have a Octavia I 1.9TDI engine code ALH, 2003 with 100k miles, one owner from new. Vehicle has gone into limp home mode with fault code 17965 / P1557 showing. Using my Foxwell NT500 code reader and live data at idle with fault code cleared N75 indicate 25%, with specified boost and actual boost both around 1000mbar. With increasing revs there is some diversity between actual and specified boost figures., with actual being higher. Once limphome mode is reached again (over 3000rpm pulling hard up hill) N75 is 'stuck' at 94.7% irrespective of load. Switching off / clearing codes works till the next time. Have tried new N75 valve (Pieburg) and all vacuum pipes are clear / not leaking. Suggestions please.

@wulfrunian - Search for "Mr Muscle fix" on this site.

Will try that (have also ordered some Archoil AR6400-D-MAX which seems to get good reviews but probably costs more than Mr Muscle!). Also tried connecting a vacuum pump directly to turbo actuator and at 15inches mercury vacuum am only getting about 5mm of movement on the control rod which does not sound correct. Nonetheless that movement is smooth and releases quickly.

10 hours ago, KenONeill said:

@wulfrunian - Search for "Mr Muscle fix" on this site.

As soon as i read the OP i thought "sticky vanes"