The check engine light came on this morning. Bank 1 is running lean. I'm thinking a vacuum issue, or perhaps an O2 sensor. But which O2 sensor? Truck had a rough idle this morning on start up. Once warm it was fine. Lighht came on after a short trip to the store. Has anyone had the same issue/code? What solved it for you? I have new plugs and Sea Foam waiting for a warm day to do, provided I can solve the check engine light issue. I have disconnected the battery to see if the code comes back. Thanks for any help.