Rep Power: 0

I own a 2012 Honda Civic EX, which I use to commute 300 miles round trip, daily. I was getting about 40 MPG during my commute, but my MPG has dipped down to about 30-31. The check engine light also came on. I had the code read, and it showed the Civic was running too lean, with the likely problem being the mass air flow sensor. I replaced the mass air flow sensor, but am seeing no change. My check engine light will come on, but then disappear and I am still getting 30-31 MPG. Anyone experience this same issue, or have a solution? Anything is appreciated, and thanks in advance.

Tyler

 
Rep Power: 243

Was it replaced with an OEM part?

Not sure when gas stations switch over to winter gas but that will drop MPG. Also a dirty O2 sensor (A/F sensor) will lower MPG.