My check engine light has been on with p0171 and p0174 lean codes for over 150 miles after installing a cai. As mentioned in a previous post I have been awaiting a new intake tube fro k&n. Well today I filled up my gas and the CEL goes out, not sure if it was right after filling up or not. When I connect my intune to read the trouble codes it still lists active codes as p0171 & p0174 even though the CEL is extinguished. My question is will the codes always be present once the computer triggers them or should they automatically clear once the CEL goes out?