Hi there -
Thank you for your info there -
With this make / model / engine system,info is not as available as some others - and too certainly - in the aftermarket ( ie, non dealer network,) the test equipment needed to trace faults down is not so available - this is because they are a lot rarer than some other makes so garages don't invest in the equipment.
So - it does need the equipment to test as mentioned above - this car has the DH D engine / fuel management system... as such, most any local Diesel Specialist should have the equipment needed to test / trace this fault down for you - so I would suggest to look up and use such a place - it seems evident to me that the garage you are using perhaps is a little out of their depth with this one - so that is what I would suggest.
As a genera rule - guide, the info on the code you have -
P0234 - Supercharger Over boost Condition The PCM ( thats the vehicle computer ) disables (bypasses) the supercharger boost and sets a fault code to keep from damaging the systems during possible harmful operating conditions. Things that can be checked are as follows - inc fuel system -
Engine over temperature .
Ignition misfire exceeds calibrated threshold.
Knock sensor (KS) failure or knock detected .
Low speed fuel pump relay not switching.
But again - your local Diesel specialist is the best place for this to get this sorted for you now with the proper equipment.
Ensure its service items are up to date first - by that I mean - fuel filter and air filter - If not - change them first and re try it. -- then go from there as / if still needed as above.
Best Rgds, MIKE.