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My ride burns way more gas than it did before I changed my knock sensor now I only get 31 miles from a quarter tank to empty why?

Answers from the Automotive Experts

Jessica Howe, Automotive Expert & Coach at


Thank you for writing in. That much of a sudden loss in fuel mileage is worth looking into deeper. It is important to realize that a faulty knock sensor can cause a drop in fuel mileage, and that the issue may all be related to the repair that was recently made. The first thing is to scan for diagnostic codes given that the check engine light is on. This will help us determine if the issue does actually pertain to the knock sensor or if there is a second issue happening at the same time. If the check engine light is illuminated due to the knock sensor, then you are going to want to verify that the new sensor is properly installed. You may also want to look into the sensor that you purchased for the repair and make sure it wasn't faulty to begin with. Only further testing will tell. Good luck!

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