Significant Drop in Gas Mileage

Discussion in 'Prius v Fuel Economy' started by Hello123, Mar 4, 2018.

  1. Mendel Leisk

    Mendel Leisk Underfoot

    Joined:
    Oct 17, 2010
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    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Prime head gasket failure mileage. You have P0301 (misfire on cylinder one), which pops up almost without fail with 3rd gen head gasket failure (usually starts at the wall between cylinder one and two).

    I'd assume the EGR cleaning was done recently, which is very late-in-the-day, should be done at least by 100K. You want to thoroughly clean all the EGR components, which is everything between the exhaust manifold and the engine intake ports, including the intake manifold. If someone else is doing your EGR cleaning, and they're not experienced at it, they've likely missed cleaning something, either the EGR cooler (connects to the exhaust manifold, is a bear to clean) or the intake manifold (didn't know it needed cleaning).

    But deal with the head gasket first, try the aforementioned leak down test and boroscope inspection.
     
    Montgomery likes this.
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