ok a couple months back i got the cel. pulled codes they were for flh 02 and the ks. i reset it planning on getting a 02 sensor when i got the money because i noticed i was getting bad gas milage after that. well it came on 1 time before i got the 02s and i got the same 2 codes with another one being the evap purge control valve/soleniod valve. so i decided to still get a 02 sensor. changed that did notice better gas milage but the other day after a 25 mile drive the cel came back on and i am now getting a code for the rear 02 sensor along with the ks. now my rear 02 sensor was replaced 2 1/2 years ago and from what ive read they last longer then that so would a bad ks be the cause of this or possibly a problem with the cc?

 

You shouldn't let one time frame determine if its bad or good. I remember on my car that I kept getting a bad front left bank 02 sensor and after proper tuning and the ECU relearning your driving habit it never came back on. Try monitoring the situation by driving 2 or 300 miles in between ECU resetting and if the CEL persists than you can make a better determination if its the Rear o2 or if its the knock sensor.