You dont need to go to renault,,
Most indipendant garages have hand held plug-ins these days.
I to have an 02 1.5 DCi 70 and have had a similar problem.
It was cured simply in minits, the
plug in is located under the glove box to the right of the fuse board.
The system on the van is a lucas delphie.
Read the codes and then clear them, simple.
My problems were fuel related as I was running on veg