I trust your Actyon's are running well, seeing that there's very few posts. I had a problem with my injector seal on the 2.0l diesel.
The first signs for me was a strong exhaust smell inside the cabin. Then looking into the engine bay you'll see a black sticky deposit forming around the injector where the seal are worn out.
Search around for the seal. I found my replacement at a diesel workshop that also sell parts.
I suggest that you act quickly to repair the seal because that makes the process so much easier. The tools needed are a 17spanner to undo the high pressure fuel lines and en E10 socket to losen the holding down bolt of the injector. A sliding hammer will also come in handy to remove the injector from the hole. A flat screw driver to "shock" the seal loose at the bttom of the "hole" will also come in handy.
Clean the area around the injector before you remove the injector. Also make sure that the Actyon are at normal operating temperature...it just makes the carbon softer to work with. Replace in reverse order.
This "how to" was given in very broad strokes but reply or correct me if there is more knowledge available.