Totally sorted saved £££££
Ok, the 2.2 DCI engine, as fitted to my 2004 2.2 DCI Mk4 has a plastic rocker cover. Now this is a complex plastic, yes, plastic cover that incorporates some of the inlet manifold. What can happen is that this rocker cover warps and you loose pressure. This causes the system to think there is a problem with the injection system... hence the errors. You will see oil
round the top of the rocker cover and when warm, air.
Renault quoted over £1000 but then said that this was a part that was covered under warranty and have covered 90% of the costs. So I only ended up with a smallish £114 pound bill.
Note, they have to strip down the whole injection system to get the rocker cover off and the injectors can break.