Actual vs requested boost and P0234 limp mode 2.0tdi

[AlAvantB7]

Today I tried to log Actual vs requested boost,with engine speed (red) and duty cycle with vcds.
Its a BRE 16v 2.0tdi.
This is the multitronic gearbox with the 7speed, so the idea was to go from 2000rpm - max, without hitting the kickdown, but it was in 4th, and went to 5th, and then hit limp mode, with a P0234 overboost code again.
I tried 3or4 times, after clearing the code, and this is the graph I got.
I have cleaned the turbo with mr muscle, replaced the N75, and had a good xmas day run for about 20+miles at 3500-4000rpm in 4th gear with no problems, so was surprised it went in limp mode today
Does this graph show anything unusual?
Screenshot_20221227_174541.jpg

[Crasher]

Mr Muscle is water based and causes the turbine shaft exhaust side piston ring to rust and lose oil control, from the graph the turbo needs properly rebuilding.

[AlAvantB7]

would that mean remove strip and clean, or replace seals,bits,etc?
I guess you cant tell until its in pieces?

[Crasher]

We send them to Midland Turbo for a quick turnaround and faultless rebuild.

[mickeybo]

The turbo pressure control solenoid is flagging up code po234 over boost. I would start by checking resistance between pins nos 1 & 2 which should read between 14-20 ohms this turbo has a switched earth at ecu no b29 Do not dismiss your fault code

[AlAvantB7]

*this turbo has a switched earth at ecu no b29*
Is that from the N75 too?
Is there something I can check at ECU B29?

[AlAvantB7]

well its working alright again today, so ***?

[Blackdubyellow]

Hi all, new to this group.
I have a VW golf mk5 2.0 GT
The issue I am having is when over 2000rpm sitting at 70/75 the car goes in to a limp like mode and I have no boost, no lights on dash and when using OBD reader a pending code of PO234 occurs. The fault stops when car is turned off and on again, then the car drives as normal for a while.
Code says overboost condition
I have had the car serviced and a refurbished turbo fitted.
Anyone had this issue occur and had a resolution?

[Crasher]

16618 (P0234) - Boost Pressure Regulation: Limit Exceeded (Overboost Condition)

If you have P0234 then either the turbo is still sticking, there is a fault with the vacuum control system or the Manifold Absolute Pressure sensor is sending incorrect information to the ECU.