okay guys, so i just picked up my car. it was running a little rough, such as jerking a little when getting into the gas after shifting, also seems to get crappy mpg. anyways, no CEL was lit up, so after buying a predator programmer, i decided to check for codes anyways. I found both rear o2 sensors had shot heater circuits, and bank 1 sensor 1 was shot, as well as a p1416. Long story short, i uploaded the "o2 delete" tune from my predator programmer, and cleaned the passenger side air valve. Now no codes show up. so here is what is troubling me...

why would the CEL not light up when codes are present? i assume someone had previously screwed with the PCM via a computer? also, why is the front o2 sensor not showing bad anymore? is it possible someone had replaced it and not reset the pcm? should i be concerned with this? The car is still running a little rough... not sure about mpg yet.

 

I do believe HP tuners has an option where it can either a: throw a code and not illuminate the CEL. or B: Not throw a code at all or C: throw both code and light. Sounds like someone screwed it up IMO. PCM will automatically adjust for a new 02 sensor after a few starts. If its running rough, change the front 02 sensors and when was the last time a tuneup was done?

 

yeah a tune up is definitely in order. i just didn't want to have to go spend $150 on a set of o2's if it was unnecessary. any other way to diagnose the o2's?