[Engine] P0234 turbocharger overboosted condition

[Berlingo12]

Hello
I have P0234 turbocharger overboosted condition on my berlingo with hdi 1.6 90 horsepower engine. 
It is my first car and my first time working with the engine so i need some basic help to get started. I find it hard to do reasearch on the issue when i dont know the name of the parts and pipes. It would be very appreciated if someone can "draw" on the picture or refere to it and name the pipes and parts i should start to check. 

I noticed 2 things today that i found strange and could possible be related: There was oil in the turbo inlet pipe, and the pipe below the break fluid container was very loose. It looked like it is supposted to be connected to another pipe 30 cm deeper in the car, but now its is loose and just laying on top of it. 

All help is very apperciated. Name, of parts, how they look, location and ofc any advice to fix the problem

[cancunia]

Welcome to the forum.
I think you may have posted in the wrong section as your picture does not look like it is the M59 model.

Turbo overboost may be due to a stuck turbo actuator, but it is unusual in the 90HP version as the 'safe' position of the wastegate is open, maybe the wastegate has stuck closed.
Can you send some more details of the year your car was made?

[Berlingo12]

thanks. i see now that i may have posted in the wrong section.

Citroen Berl-la 90hk Plus, the car is from 2011

[saskak]

Not too sure if the 2011 is as similar to the M59 as I think it is, but by looking at the picture, overboost is either stuck wategate, but not likely as cancunia said.
The other possibility is the turbo solenoid at the very back of the engine. These get stuck and do not relieve the pressure and the wastegate is always compressed. There is generally a pipe that comes off the solenoid and goes to the top of the engine. Mine is clipped between injector 2-3. These sometimes get clogged, but in all likelihood it is the solenoid. Pretty cheap to buy/clean, but difficult to get to. It's just a couple of bolts and a few pipes.

[cancunia]

Not too sure if the 2011 is as similar to the M59 as I think it is, but by looking at the picture, overboost is either stuck wategate, but not likely as cancunia said.
The other possibility is the turbo solenoid at the very back of the engine. These get stuck and do not relieve the pressure and the wastegate is always compressed. There is generally a pipe that comes off the solenoid and goes to the top of the engine. Mine is clipped between injector 2-3. These sometimes get clogged, but in all likelihood it is the solenoid. Pretty cheap to buy/clean, but difficult to get to. It's just a couple of bolts and a few pipes.

From looking at the engine cover in the pic, it looks like a 16v, if so it will be be just about the same as the M59 engine. 
I can't remember exactly but isn't there a way to do a quick check of the operation of the acutator? Something like 'start the engine and it will move one way then the other'? I suppose if the solenoid is stuck open, you'll get constant vacuum on the actuator.

Mods - If you see this, please can you move it to the B9 section?

[Sol]

There is always oil in the turbo intake pipe I'm afraid, it is from the breather connection to the rocker cover, so that's normal. Also the pipe under the fluid reservoir is the intake tube from the cold air duct to the airbox, they are famously loose and flimsy. Neither of these things can be anything to do with your issue.

As the others said, this is the older 16v engine and the turbo boost is controlled by a wastegate and an actuator for the wastegate. You can watch the actuator and start the engine, it should move somewhat or use a vacuum pump (handheld ones are cheap on eBay) and connected to the actuator it can be used to make it move. But, default as said, is open which should give no boost at all.

If the wastegate is stuck closed, it will need removal of the turbo heatshields on the front so you can see if the arm is free or jammed. This is visible on the hot side of the turbo with the covers off. It should be possible to move it by hand once it's visible. (With the engine off and cold)

One thing I wonder about myself, is if the wastegate hole is plugged with carbon from the exhaust gases - maybe lots of short journeys while not properly warmed up and idling for long periods while cold could build up soot in the port of the wastegate valve.

It operates like a key on a saxophone, it's a machined disc which closes neatly into a shaped hole to produce boost and opens to let exhaust gases bypass the turbo and go out of the hole. If the hole is plugged or the valve jammed shut, it would over boost.