Toyota Highlander 2005 was having fuel issues so replaced pump, regulator and strainer, had to buy original Toyota pump since we tied to others and didn't work and gave codes p0171 and p0174 it's having trouble starting so we cleaned the MAF sensor and engine started immediately but when turned off again it takes a couple seconds to start but the car runs smooth and very strong but fuel efficiency doesn't seem so good and codes haven't returned in one day so should I just replace the MAF sensor?? All this started at the same time my alternator went bad and apparently gave an overcharge and messed up my headlight and two tail lights and my car rattled so someone very experienced told me it was the fuel pump didn't have enough pressure and the car does not rattle anymore but just has a bit trouble starting for a few seconds.. thank you
My car has 173800 miles.
My car has an automatic transmission.
Several things may cause code P0171 and P0174 to be triggered. As the codes indicate, there is a lean fuel condition present, which may be caused by a lack of fuel supply or in some cases, a vacuum leak. When a vacuum leak is present, this introduces an excessive amount of air into the fuel/air mixture which results in leaning out the fuel content. Other problems such as a faulty fuel pressure regulator, a faulty fuel pump, a clogged fuel filter, faulty fuel injectors, faulty oxygen sensors, or a faulty mass air flow sensor may also cause this to happen. I would suggest having a professional from YourMechanic come to your location to diagnose and inspect your vehicle.
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