Q: Error code P0171 and P0174

asked by on November 21, 2016

I used the OBD II / EOBD CODE READER and found the following code P0171 System too lean P0174 System too lean Freeze Frame: DTCFRZF P0171, Fuel sys 1 CL, Fuel sys 2 --, Load_PCT (%) 75.29, ECT( ‘C) 78.00, SHRTFT1 (%) 0.00, LONGFT1 (%) 25.00, SHRTFT2 (%) 0.00, LONGFT2 (%) 25.00, MAP (kPa) 47.00, RPM(rpm) 705.50, VSS(km/h) 0.00, SPARKADV 4.5,
IAT(‘C) 00.00, MAF(g/s) 6.28, TP(%) 18.43, I don’t feel anything while driving the 2006 Ford Five hundred SEL, It accelerates well and goes easily to 40miles per hour when given the acceleration (I have not tried beyond 40 miles/hr in order to avoid any damage, as I bought it recently and want to repair it before use) the odometer reads about 200,000 miles, what can be the possible reasons of this errors and what should I do to make it a smooth running vehicle?

The high positive long term fuel trim suggests a vacuum leak and/or inadequate fuel delivery. But there are other causes that have to be evaluated as well: bad oxygen sensor(s); dirty MAF sensor; stuck open EGR valve; weak fuel pump; restricted fuel filter; leaky fuel pressure regulator; dirty fuel injectors; and exhaust restrictions such as a clogged catalytic converter. In addition on Ford models, a well known issue is that P0171 and P0174 lean codes can occur if the EGR differential pressure sensor goes bad. After 6 years or 60,000, that sensor is reported to have a high failure rate. If you desire that your vehicle’s lean operating condition be diagnosed and corrected YourMechanic can dispatch a certified Mechanic to your home or office and perform a mobile diagnostic and repair. Please let us know if you have additional questions or concerns.

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