Matt Sayre

I have had a new motor in my 2007 Suburban for about a month now. I have P0174, P0300, and P0521 codes throwing. It is causing my mpg to go down some, check engine light on, and stabilitrac and traction control to turn off. I also feel like the ABS is engaging a little at speed. My service suspension warning is on too, but I believe that to be a separate issue. I have also replaced the oil pressure sensor before. Please let me know your ideas or questions.

Spencer D.

Your P0174 code reads "System too lean" which could be why your mpg has decreased. Try checking your MAF sensor to see if it is dirty or possibly just loose. The P0300 "misfire" code can coincide with the "too lean" code because a dirty sensor will set it off as well. Have you noticed anything different with the exhaust? As for the P0521, that's a performance code relating to your oil. You said you replaced the oil pressure sensor before, is that because it went bad or it was throwing a code and you figured replacing it would fix it? Did it fix after you replaced it? When was the last time you got your oil changed?