Hi

I did a scan via FORscan, and have a Code: P0234 - Turbocharger/Supercharger 'A' Overboost Condition. (I have attached a picture of the fault)

I did this scan on the back of "engine malfunction service now". 

Does anyone know what part of the Turbo is an issue, or is the whole turbo part need replacing. Would really appreciate some guidance on this. 

Many thanks 

 

 

 

 

 

Probably not the turbo. The fault code shows it overboosting. So it is producing more than enough boost, right? Your problem is likely to be due to a loss of the vacuum to the actuator solenoid; busted pipe maybe. Or the solenoid itself. These components amongst others control the maximum boost pressure  Fault codes need to be interpreted. It doesn't say the turbo is faulty as such. 

45 minutes ago, anon said:

Probably not the turbo. The fault code shows it overboosting. So it is producing more than enough boost, right? Your problem is likely to be due to a loss of the vacuum to the actuator solenoid; busted pipe maybe. Or the solenoid itself. These components amongst others control the maximum boost pressure  Fault codes need to be interpreted. It doesn't say the turbo is faulty as such. 

Thank you for the reply - much appreciated. Very good point. 

Currently the car is in "limp mode"...it doesn't rev above 4k. 

Are these easy to replace? 

I'll try and have a look tomorrow to see for a sign for a burst pipe. 

This may be relevant:
https://www.fordownersclub.com/forums/topic/162662-16-tdci-turbo-question/

 

Hi,

 

Thank you for this. I somewhat understand it and was hoping for further clarification. 

Where abouts in the engine bay do I start to have a look to identify where the solenoid is?

Apologies, I have some knowledge of working around the engine, quite basic in some elements but I just need some guidance of where to navigate in the engine first. Happy to provide a picture? 

 

 

If not in the suggested thread (haven't looked) the it should look like this :

https://www.youtube.com/watch?v=dkPuEmwP4oQ

Likely brown, you'll need to identify the two pipes (one from the vacuum pump and the other to the turbo)

There are multiple video showing how to test but disconnecting and plugging the pipe may change the fault code.

 

On 7/31/2025 at 9:34 PM, Shearers said:

If not in the suggested thread (haven't looked) the it should look like this :

https://www.youtube.com/watch?v=dkPuEmwP4oQ

Likely brown, you'll need to identify the two pipes (one from the vacuum pump and the other to the turbo)

There are multiple video showing how to test but disconnecting and plugging the pipe may change the fault code.

 

Thank you. I can see the actuator solenoid seems to be working as it is going up and down. Safe to rule that out?

Move on to the solenoid to review as per the video you sent?

I can't seem to find a replacement for the solenoid as there's different variations. Any chance you could share the part number or link (in case required)

Sorry, I don't know your engine or if it's wastegate or variable vane turbo and always best to check parts are correct with supplier using reg or VIN.

If the vacuum actuator on the turbo is "working", that's  start but if it's got the overboost code and after clearing, it returns, there's obviously a fault somewhere.

It may still be the solenoid valve that controls the boost or wastegate so my next step would be to look at live data to see if there are any PIDs for demanded boost and actual boost plus other related pressures (e.g. MAP sensor) and all vacuum pipes for splits/leaks etc.

Could also disconnect pipe to turbo actuator and note the effect of that?

As usual, unless someone else can go straight to it?

Thank you for the reply. I have attached a picture of the faults that came up on the scan. 

Is the solenoid the top circle? Thanks

3 hours ago, Fadbrt said:

Is the solenoid the top circle? Thanks

No.  That's the purge valve.  (Although technically that is also a solenoid).

The boost solenoid is roughly between the silver turbo shield and the airbox near the front of the engine bay.  Can just about see it's yellow top hat in that picture.

29 minutes ago, TomsFocus said:

The boost solenoid is roughly between the silver turbo shield and the airbox near the front of the engine bay.  Can just about see it's yellow top hat in that picture.