




Need help reading o2 sensor on 2004 Chevy Trailblazer 4.2
I’ve been slowly trying fix this thing, got it in an emergency. I’m trying to find the source of some poor gas mileage, misfires, stuttering, etc. and I’m slowly but surely ticking boxes. Spark plugs and ignition coils have all been tested (with a multi meter), all evap systems are now good and passed smoke testing (intake manifold and evap solenoid and vent replaced) vacuum line on fuel pressure regulator and fuel filter replaced, air filter replaced, throttle body cleaned and reprogrammed, 2 cycles of fuel injector cleaner, MAP sensor cleaned. There is no MAF sensor or PCV valve on this truck. Obviously the oxygen sensor is “working” but is it fouled or giving any hints to what I can look at next? Including photos from driving and idling