So now it's saying PO172 system too rich.... Two days ago it was system too lean. I am going up an elevation and down in the mountains could that have anything to do with it?

2007 Hummer H3I5
148k miles
Air doc

 

Is your air filter clean?

Yes, elevation can have an impact if extreme.

 

I just sprayed out the air filter and tried it and everything yesterday
It's a reusable one that we get here in Arizona because of all the dust. I can pull over at the nearest auto parts store and get a new one if you think that would help
I was at 1,000 elevation that went up to 4300 and then to 7,000. First it was the engine too lean now it's the engine too rich. Do you think it's the O2 sensors?
the two lean code disappeared on its own when I got to Sedona but I went ahead and replaced the spark plugs cleaning the MAF sensor and MAF assembly and clean the air filter anyway. When I hit 7,000 ft it popped engine too rich

 

Don't jump to conclusions with the o2's, you can check fuel trims to see they are operating properly. Get back to the basics, start with a new oem type air filter, then clean the maf sensor again with a quality maf cleaner, and make sure the cai is properly secured after completion.

 

I went ahead and purchased an disposable air filter from autozone (STP) and the MAF sensor cleaner I already had, exact same one you have pictured. The code went away and didn't come back, drive about 60 miles. Doing a 3 hour drive home today so well see what happens. Thanks so much for all the help