p0234 overboost help

[Mullan]

Recently my car has gone into limp mode 3-4 times when using a heavy foot. The code read was P0234 which is overboost.
The car is a Mk5 TDI 140 BKD engine type.

I've read about it and there is a lot of new turbo comments. I've had the car taken to a garage and independently checked which has resulted in unsure on what to do. I picked the car up this evening and the conversation was left at "see how you think and get in contact." I have since produced overboost so I am still in the situation.
The mechanic currently is reluctant to suggest a turbo due to pricing and trouble shooting. He has suggested a mass airflow sensor or N75 valve as potential issues.
My trouble is I do not want to get into a situation where I need to overtake and limp mode kicks in.

There is also a glow plug code currently on the car which I will be replacing.

What should I do next?
Thanks for your time.

[doylebros]

Does it make the noise as though the old bill is coming up behind you?

If so go the replacement turbo route, if not further testing would be my line of action!

Bit extra advice here

http://www.myturbodiesel.com/1000q/multi/limp-mode-TDI-fix.htm

[Mullan]

Sorry, to clarify, there is no abnormal noise, no whining etc.
I am concerned that since the limp mode first occurred, power does feel down ever since but that might just be in my head.

[doylebros]

How mechanically mind are you and what equipment do you have access to,for undertaking further testes?

[Mullan]

How mechanically mind are you and what equipment do you have access to,for undertaking further testes?

Mech engineer by trade but no access to ramps or testing equipment really. There was tests done at the garage today which I will clarify with a phone call tomorrow. Reading the link above, MAF sensor can be ruled out?

[doylebros]

Spend sometime reading that link (as well as the links off it) - there's a lot of simple issues which can cause your fault.

Whilst being mechanically mind and having limited access to the required tools, it's going to be a frustrating time.

YouTube used to have some interesting videos on this subject look there.

[Roadrebel]

My Mk4 GT TDi does it. I am fairly certain that it is the actuator that alters the turbo vanes that is causing the problem. It sometimes sticks (or it could be the vanes sticking)  which allows the turbo to give too  much boost at low revs and when the ECU detects this it goes into limp mode. It re-sets as soon as I turn the ignition off and on again.

A good turbo clean may cure the problem but I have found that putting the engine under a good load up a long hill helps to clean the crud out and makes the problem less frequent.

HTH

[Degudodger]

My last GT TDI 170 had the same issue where it would go into limp home mode after rapid exceleration. Replaced the boost controller and it cured the problem.
http://www.mk5golfgti.co.uk/forum/index.php/topic,71239.msg767445.html#msg767445