Right.. but sometimes not immediatly. And besides, he won't know if the car won't stay running. CEL stays lit when the key is turned to accesories, and thats as far as he can get. It wouldn't have thrown a CEL immediatly when it was running for the 2 minutes. In my mind, it all makes sense and is a very big possibility. Forgeting to tighten down the cap would lead to all of this.

2006 Pontiac G6 3900SFI GTP Coupe CAI, Stainless Cat Back, Vector Tune, Strut Brace, Eibach Pro Kit, Custom Made Projector Headlights, 4300K, 20% Tint Former Owner- 2000 "Stryped" CSVT CEG Dragon Run- Oct 13-15