For P0171 and P0172 it never is easy to get to the cause of the problem as there are too many possible reasons.
System is running rich and a clogged air filter can be the cause. That would be the easiest and least expensive of it. Other than that, O2 sensors, fuel pressure, regulator, MAF etc and further testings would be required.
Saturday, October 13th, 2012 AT 10:04 PM