You have a number of options here. If your sensors say your running lean, chances are there is a problem with your fuel system. This happened to me all the fu**ing time when i owned a DSM (91 Plymouth Laser). Try running a fuel treatment system like STP in your car because it could be just a plugged fuel injector. Try the STP type stuff first because if its saying you are running lean multiple times you might just have carbon build up that needs to be taken care of. Also, it might just be a faulty o2 sensor which just means you need to replace it. try all these other remedies first and then take it to your mechanic. and...run 93 octane.RLee said:I have a Service engine light on. The fault code is PO174, bank 2 to lean. Had this fault before (0171, Bank 1 to lean) 6 weeks ago.