the MIL light just came on today. It's not acting strange or anything, but it has at least 50,000 miles on it (it's a 2005 model). My dad and I aren't very good with new vehicles- what's the computer saying is not doing what it should be doing?

After eading the manual, am i correct to assume the O2 sensor needs to be checked/replaced? the truck has 52,195 miles.

 

scanned it at dealer..EGR valve...