Possibly have a problem in the vacuum hoses that motor actuators move through the solenoid valves.
I explain myself, the management of the turbo, the EGR, and something else, goes by emptiness through solenoid valves.
If a solenovula fails, an unequivocal code appears automatically in diagnosis (EGR actuator failure ... Falling Pressure Actuator failure ...) whatever.
Peeeero if a vacuum hose fails or if the engine vacuum pump sucks little, the solenoid valves work, but the problem is that the actuators do not move on time !!
So: the EGR fails because the switchboard orders to open it but it does not open, or not as it should, the turbo feed pressure fails because the lung that limits the blow is operated by emptiness and does not work correctly ... the flowmeter fails because it measures a lot of air (when the turbo blows and does not touch to blow for example) and gets out of range ...
summarizing, fifty failures and none is 100% correct. All for a fucking plastic tea that has broken or for a shit tub that has fallen ...
the first thing, check all the tubes that leave the vacuum pump and check with a vacuometer that there are no vacuum leaks or perforated membranes in the actuators.
Another thing that gives enough war is the intercooler, sometimes it is drilled or slit, or some turbo sleeve is broken and causes the compressed air of the turbo to escape to the street. This causes failures in the feed pressure sensor, black smoke, failures such as the flowmeter is wrong or as the EGR is damaged.
To rule out this, apart from visually checking the sleeves, the intercoler exit mushy is touched to the intake manifold, the flowmeter is disassembled and another plug is put in the sleeve that embraces the flowmeter.
Then the 1.5 bar sleeves are pressurized at most and if a pffffffffffff (blow by somewhere) is heard, it means that we have found the breakdown.
If you had started there, you would have saved money.
All the best.