Code 52, knock sensor. Mmm. I just got done dealing with mine. FWIW, if I drove slow my check engine light wouldn't come on, but the second I started getting up over 2500 RPM the light would come on. It turned out to be bad wiring which I fixed with Shaeffs knock sensor rewire kit. You're lucky you only have one knock sensor if you need to do the rewire or change it. The rear knock sensor was a BITCH to get to.