SES light on my 04 2500HD?

[vortec bigblock]

The other day the ses light came on. My truck is onstar equipped, so i contacted them for remote diagnostics. There reply was that it had to do with the fuel control module and or powertrain control. The only other ses light in 40,000 miles has been caused by a bad 02 sensor. The only adverse effects i have noticed, if any, is that it idles kinda rough on a cold star. Its also been much colder lately so who knows. Just wondering if there is any chance of this ses light being an 02 sensor based on the remote diagnostics.

[GM-Tech]

I've talked to OnStar about their "remote diagnostics". They don't tell you squat. They only tell you it's possibly emission related and to go to a dealer.

 

So, find out the actual DTC and go from there. Don't make any assumptions based on OnStar's comments.