The intercooler is usually situated in front of the radiator. The inter cooler is connected between the turbo and the air intake into the engine. It is designed to cool the 'compressed' air from the turbo charger. So follow the air pipe from the turbo to the front of the van behind the grill.
There is a diesel inter cooler under the van with fins on it, but they will have small fuel pipes coupled to it. This is coupled to the diesel return pipe to the tank and is to cool the hot diesel before it gets back to the tank.
You need a mechanic that has access to the citroen fault computer codes. The ECU can clear some faults when the fault has been identified and rectified, but some have to be cleared on the computer. Some will try the old trick of disconecting the battery terminal for 60 secs with the ignition on, but you might have to get the codes cleared at a Citroen Garage.
If you haven't got the engine management code (key/password) then Citroen will get it from France but you will be charged for that service as well.
Robertphil has posted a good suggestion. Bearing failure due to poor lubrication is the most common turbo fault, but as Robertphil has said, turbo failures on the 2.0 are very uncommon.