My engine check light came on and I had it checked with scanner and it shot out a code that read p0171 what do that mean and how do I take care of it

Asked by Dec 11, 2013 at 02:04 AM about the 1999 Ford Expedition

Question type: Maintenance & Repair

The engines check light does it cause the
interior light to come on to I drive a 99 ford
expedition 5.4 liter v8

1 Answer

257,535

code P0171 may mean that one or more of the following has happened: •The MAF (Mass Air Flow) Sensor is dirty or faulty Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry. •There could be a vacuum leak downstream of the MAF sensor •Possible cracked vacuum or PCV line/connection •Faulty or stuck open PCV valve •Failed or faulty oxygen sensor (bank 1, sensor 1) •Sticking/plugged or failed fuel injector •Low fuel pressure (possible plugged/dirty fuel filter!) •Exhaust leak between engine and first oxygen sensor

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