Is there a resource online for looking up DTC codes? My SES light has come on 4 times already and I only have 1300 miles on the truck.

I called OnStar but they are pretty clueless about the specific codes and I don't have my service manuals yet.

Anyway, here are the codes that set so far:

Date Miles Code Description
8/29 1150 P0181 Fuel Temp. Sensor 1 Circuit Performance H H P
8/31 1266 P1683 Driver 5 Line 3 H H P
8/31 1268 P1683 Driver 5 Line 3 H H P
8/31 1289 P1683 Driver 5 Line 3 H H