I know this thread is old but it should help anyone like me who comes looking for answers. I Just had this problem with my 2008 Saturn Aura XR. The U0073 code refers to the Body Control Module not having a solid connection anymore. This causes a variety of problems that are not really problems. Here is a fix I found that worked like magic for me and anyone with a 2008-2009 Saturn Aura can do, and hopefully help owners of others vehicles.
Remove the passenger side kick plate (Saturn hides your electronics here) If you are sitting in the passenger front seat, just to the Left of your Left leg is a "side panel" just below height of your ash tray. Pull gently from the front of this panel ,you'll see a small hole to grab,(velcro there) and gently unsnap a little at a time. Panel will come off.
Find the Body Control Module (you will see several fuses and connectors attached to it. Look for the two that appear to be housed by a small plastic harness(Mine had blue colored plastic). Fit a flat head screw driver into the latch, and unlock the plastic harness (it will slide upward over the module). You can then unplug the modules and you'll see numerous tiny thin metal prongs that it snaps onto. Get some DiElectric grease from you local parts store and take a small paint brush (1/4" type) and swab the grease onto each of the metal prongs. Snap the module in and out a couple times to spread the grease around, and then snap it in and lock it down. Do the same for the other module. Then put the panel back on and drive it. My problems were cured, I hope the same for you.