pulling codes of 1336 and 1337 for ckf sensor for about a year,the car runs great so i'm not too concerned..it started out as 1336 intermittent and now is also 1337 which is no signal..so i think it is the wiring has been abraded over time by timing belt rubbing against it...no rough running etc..i may ignore it but in the back of my mind i keep thinking that if i do have a fluctuation problem in the future i won't know about it..any thoughts or observations.suggestions.......