Some 2018-2020 F-150 vehicles equipped with a 5.0L engine may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTCs) P0171, P0172, P0174 and/or P0175. This may be due to incorrect flex fuel learning, which is often caused by customer refueling habits when adding only small amounts of fuel, the vehicle mislearning of inferred ethanol fuel mixture (FF_INF value) or a component concern. Refer to pinpoint test H in the Powertrain Control/Emissions Diagnosis (PC/ED) Manual for diagnostics and Flex Fuel GSB for additional flex fuel system information and diagnostic tips.
