I'm having trouble getting the O2 monitor to run so as to pass smog.. I've tried everything except changing the upstream sensors. Would a not bad enough sensor not throw a code or cycle the check engine light ? also, would a faulty O2 sensor cause it to not run the monitor ? 2010 5.7 with 214708mil. looking for any suggestions before I just switch the sensors.


Thanks,
Dom

 

Without being able to see and diagnose O2 data, your only option is to change parts.