03 Renault Trafic, Cut-Out And Engine Management Light Appeared, Still Runn?

Hey, I have a 03 Renault Trafic with 150,000miles on it. Have had egr valve, airflow meter, new clutch and a few other things replaced on it so all the common faults have been fixed. I was driving home yesterday and after 2 and a half hours driving I pulled into side of the road for a rest. When the van stopped it just cut-out. Stop and engine management light appeared and the van started up straight away with no trouble. I drove home and the van felt the exact same as before and starts up grand. Why would these lights stilll be on? Also is there anywhere to get manuals like haynes manuals for these vans cause I really want to be able to do stuff like this without splashing out a few hundred euro for a mechanic to rip me off. Thanks for the help.