Does anyone know what PO172, Lean Bank 1 could be? My check engine light randomly comes on and off when im driving and i had it checked out and they told me the code and said that it would take another hour or two to do a full diagnostic on the car to see whats wrong but they said it could be a vaccuum leak or something wrong with the intake...i had to be somewhere so i left and they wont be able to look at it till next week. Ive also noticed that my car seems to "stutter" sometimes or it seems like the engine might be a struggling a little bit, and every once in a while when im accelerating it sounds like it will stutter and the rear axle will make a quiet pop noise and i know somethins acting up every once in a while...could this have anything to do with the check engine light?