A few weeks ago I had my boy in Orlando temporarily lightly tune my car and one of the things he did was delete my cat code p0420 so I could get rid of the check engine light. Since then my gas mileage has dropped some and my boy explained to me doing that threw my fuel trims off which seems correct. So on Friday I plan to go back and get a full tune from him and he said he will probably just turn the code back on but before he does that is there anyway around having my check engine light on while having the code open so my mileage goes back up?