Question

1998 Ford Expedition 4.6L, codes p0171 and p0174 showing at the same time both o2 sensors have been changed any suggestions what may be the problem?

Answer 1

Hi there,

Usually if it's affecting both banks it's either a problem with the mass air flow sensor or an issue with low fuel pressure. Sometimes intake manifold leaks can also cause these codes, but normally when that happens you have misfire codes as well.