Hey guys I have a 1995 Nissan Altima, 2.4 liter. I was getting a PO325 Knock Sensor Code so I replaced the knock sensor. I am getting poor gas mileage, and am afraid I am damaging the engine.

The code came back on the day after I replaced it.

What else should I check over? Thanks for any input.
-Pat

 

Could this be coming on because of lack of running premium fuel? 91+ octane? I did my headgasket and had the head machined slightly below spec.

 

Anyone have ideas?