Q: P0171 and P0174 codes

asked by on October 06, 2016

My check engine light came on for bank 1 and 2 upstream o2 sensors. I smell raw fuel from engine compartment, and my fuel tank crushed itself causing a hole in the tank. All this occurred after I replacement my fuel cap when the light came on for faulty cap. I've read the vapor canister purge solenoid is the culprit. Is there any truth to that?

For one, these codes are for a lean condition and are not O2 sensor specific codes. It is true that some of the newer Fords have an issue with the purge valve staying on, putting a vacuum on the system that causes the gas tank to collapse. In fact, there is even a technical service bulletin (TSB) regarding this issue, but it does not apply to your vehicle. One thing I would look at first, is the mass air flow (MAF) sensor. There is a TSB 98-23-03 regarding the codes you have setting as a result of a faulty MAF. Of course, Code P0171 and P0174 can be set by anything that causes a lean condition; from a vacuum leak to a faulty fuel pump. To know for certain, I suggest you have a professional, such as one from YourMechanic, diagnose and repair your vehicle firsthand (https://www.yourmechanic.com/services/check-engine-light-is-on-inspection).

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