Fuel mileage drop

Is the Check Engine light on? If so, there will be at least one diagnostic fault code that will lead to the problem.

That big of a drop is usually caused by a leak in the fuel line. Look along the right side between the two wheels for spots where you park.

Listen and feel for a misfire too. A defective spark plug or wire will cause that cylinder's unburned air and fuel to enter the exhaust system where the air will be detected by the oxygen sensor. That will tell the Engine Computer to add more fuel in a misguided attempt to fix the lean condition it thinks is present.

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