Mustang1994

Is that the o2 sensor that is making the code come up? If so which one would it be.

DjBootleg813

Yes that would most likely be the 02 sensor.. Funny thing is I just had the same code and I swapped both my sensors.. Both were really dirty/burnt up.. But bank 1 means driver side.. Bank 2 is passenger side.. In this case if it is the 02 sensor it would be the first sensor on the driver side.. There is a total of four 02 sensors on our cars, two in the front and two in the back.. The front ones measure the A/F mixture the rears tell if the Cat's are working properly.. Swap it out.. But before you spent the money on a new sensor try cleaning the MAF (mass air flow) sensor.. located in the air intake.. It could be dirty and making the reading off thus giving it a lean code.. Just google or youtube how to clean it.. If that doesn't work swap the 02... Hope this helps!

cliffyk

Bank 1 is the passenger side:



As to P0171, here is what the shop manual says about it--note that "bad O² sensor" is not even on the list of possible causes. This DTC is being thrown because one of the possible causes in the list is making the AFR lean and the front O² sensor on bank 1 (passenger side) is working and reporting the lean mix.

Work the list from top to bottom, an exhaust leak at or near the sensor would cause just one bank to report lean, or a vacuum leak in the manifold. The other possibilities would like affect both banks.

rygi23

If your problem isn't an o2, intake and exhaust modifications can cause it as well. I got the same code when racing my Mach after adding longtubes, adding a touch of fuel with the tuner solved it, obviously can't do it that way with your 94 though.

cliffyk

He has a '98 in his "garage", but a '94 in his name and profile. The '94 would not be OBD2 and would not/could not throw an OBD2 DTC...