denali "service engine soon" light on steady.

This morning after starting my denali the service engine soon light (picture of the engine- left hand of gauge panel)came on and is staying on steady. I looked in the owners manual and it states that if the light stays on constant then it is a emmisions problem. Anyone have any ideas? greatly appreciated...

If it doesnt go off after a few days you will either have to take it to a mechanic, or buy a scan tool and retrieve the DTC yourself. Of course that doesn't FIX anything. So you'll have to choose again -mech. or DIY. Or you could just ignore it...

Could be the gas cap isn't secure, happened to my 99 Yukon. Did you just fill up? If so, retighten the cap and see if that does it. If it starts to run rough or any other problem, by all means stop and have it checked.
HTH,

MW