Hi guys new here found this forum while searching for help with my truck. I have a 2014 gmc all terrain crew cab it's at about 53000 miles and keeps getting a p219 left bank lean code. Fortunately I have the gm extended warranty til 100,000 miles. The pathetic dealer has been diagnosing it since before thanksgiving. Goes like this, light comes on call them drop it off. They keep it for anywhere from 1 day to 3 weeks. They call say it's good take it home next day light comes back on. The best part is if the light goes off before I get there then they say they can't work on it because there is no light on. I filed a claim with gm but they keep telling me to take it in for diagnosis. Any help would be greatly appreciated. I'm about to drive this thing off a cliff !