renault clio 1.5dci egr/glow plug faults?

2004 clio 1.5 dci .I have an OBD2 diagnostic tool which shows 2 faults 1 egr valve (which I have replaced) and Glow plug module control circuit . I suspect these faults are linked . When I clear the faults the car will do one or two journeys then the warning light will come on , all the time the cars performance is fine , can anyone help ?