not always. codes don't get thrown till they degrade to a certain point. i haven't re-read the entire thread so i don't know if this has been mentioned. the injectors could be mechanically leaking, which would cause horrid gas mileage and not throw a code. also i had a 2005 Matrix that would constantly throw the cat code and i replaced the rear o2 sensor hoping that would fix it, the cat was clear, and i find out that that car was intended for the canadian market which doesn't (at the time) have the ethanol blend and find out that the computer needed to be reprogrammed to account for the ethanol. my fix was putting an extension on the rear o2 mount moving the rear o2 sensor out of the direct path of the exhaust but still somewhat in the path. the code didn't trigger and mpg improved, but i don't recall how much it improved.Also... Is ANYONE going to answer me about how IF the 02 sensors/cat were the problem, THEY'D THROW A CODE?!
To answer your question, you need to post data.Also... Is ANYONE going to answer me about how IF the 02 sensors/cat were the problem, THEY'D THROW A CODE?!
This comment here tells me to look into the transmission before anything else.It just takes FOREVER for it to shift (even with O/D on).