I have a 56 plate Renault Trafic 1.9TDI and the service and coil light have started to come on intermitantly when they come on for a few seconds the engine goes into chugging mode for a few seconds then they go of and no probs .
Lift the engine cover and airbox and check the injector wiring for signs of chaffing. Also worth cleaning the egr valve out as these get seriously clogged on the 1.9 dci engine.