hybridbear Posted July 25, 2020 Report Share Posted July 25, 2020 Has anyone had fault code P0171 before? My parents' 2013 C-Max Energi just ran out of warranty 3 weeks ago. They had bought a 7 year Ford extended warranty for it. And now basically every time the engine comes on it throws this fault code. It would be nice to have some idea of what is failing versus having to spend a lot of money to have Ford diagnose & repair it. Thanks! Quote Link to comment Share on other sites More sharing options...
Zathrus Posted July 25, 2020 Report Share Posted July 25, 2020 (edited) The following is from Ford CMax 2013 OBD Manual and may be useful...if accessible, you might want to check connections of the molded plastic hose on the oil separator assembly (shown in red below) Edited July 25, 2020 by Zathrus Quote Link to comment Share on other sites More sharing options...
hybridbear Posted August 1, 2020 Author Report Share Posted August 1, 2020 That’s really helpful, but that info kinda looks like a gas C-Max from Europe...I looked under the hood at my parents’ C-Max & I think the engine in the diagram might be a 2.0L 4 cyl engine from a European gas C-Max. That was the challenge I had in searching that prompted me to come here, every result I found online was about gas C-Maxes from Europe. Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted August 1, 2020 Report Share Posted August 1, 2020 Well P0171 has lots of potential causes. There are fairly detailed tests / checks for the probable causes in the SM. I can see a dealer spending several hours running through the numerous checks in the SM and may find nothing. Assuming no other fault codes and looking at the list (which I believe may be in order of mostly likely cause): I'd eliminate bad fuel (high ethanol content) by switching stations on the next several fillups (parents haven't been using E85 pump as it is cheaper). You can check ethanol content by mixing water and the fuel, shaking and then look at the separation of the water from the fuel. Since Ethanol absorbs water, the filled amount of water will be less than the separated water. There are charts that will give an approximation of the ethanol content of the fuel and mixing volumes. I'd puts a double dose of fuel injector cleaner in the tank (maybe next two tanks). I would also think that if the issue were low fuel pressure, there would be other DTCs. To get to the PCV, the intake manifold must come off (note there is no manifold on the pic posted above). Quote Link to comment Share on other sites More sharing options...
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