O2 sensor monitor not ready

Eric25024 · February 8, 2020

Have a 2013 Sierra 1500 5.3 liter. Went to get truck inspection and O2 monitor and heated O2 monitor say not ready. Drove 85 miles, brought back to inspection station and still not ready. Any advice? Thank you

davester · February 8, 2020

Find out the driving conditions that are likely to cause those test to be run. They vary for the specific test that hasn't been run. I know the full-service manual has info on them, don't know where else to get that info.

And maybe get a code reader good enough to show you if those monitors have run or not. It'll save you the time and money from having your vehicle re-tested just to find out if these monitors have been run... Note, using a code reader to clear codes, can/will reset some monitors to need to be run again, so you may wish to avoid doing that, even if your vehicle has codes (it can have codes even if the CEL is off).

Eric25024 · February 9, 2020

System seems to have gone backwards. Now I have catalyst, evap, O2, heated O2 and egr monitors not ready lol. Put almost 200 miles of highway/ local driving and it seems to have gotten worse. The shop I went to plugged in there scanner and got 2 weird codes that they dont no what they are. There was no "P" code. Just numbers. Was told it's a GM issue. I tried to do a drive cycle but it's almost impossible on the roads. Going to drive for a few more days and take it from there. Also no check engine light, truck runs fine. Anyone have any similar issues?

Edited February 9, 2020 by Eric25024