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?

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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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