Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › Too lean bank one p0171 › Reply To: Too lean bank one p0171 March 5, 2020 at 9:23 am #942657 Richard KirshyParticipant Considering the parts already changed, you might look into the following. Dirty or faulty mass air flow sensor Vacuum leaks – PCV hose, vacuum hoses, intake manifold gasket. Weak fuel pump Exhaust leak