New symptom.

CEL has been on for months, rarely turning off for more than a few minutes.

It's been off for many hours of driving now that I'm at a high elevation (I live at around 50-100m elevation).

Right now I'm around 1500m, and even in Calgary at ~1000m, the CEL stayed off and did not turn on. I've been at high elevations for several weeks now and racked up a few dozen hours of driving.

I'm assuming that the engine is operating within normal parameters when the CEL is off. I would imagine that the thinner air is allowing the engine to operate within acceptable parameters. Thus, maybe it's not a leak: A friend of mine, who I saw in Calgary, was saying that O2 sensors can pass OBD2 onboard tests from the ECU even though they're actually junk.

So I'm going to try replacing the O2 sensors... despite the heavy cost.

I will report back with any changes.

@Zero0575

FYI - the air box not being fully sealed/seated was definitely my issue. This was months ago and my CEL hasn't come back on

Well, it seems that was probably my issue as well.

There was no outward evidence that the air box, filter, or whatever wasn't fitting correctly, though.

After returning to the lower mainland, the CEL eventually returned after a week of driving. But putting the aFe intake in seems to have resolved all issues.

Are your cats going bad? That would possibly cause you to run rich. Your downstream sensor sending improper values to the ecu. Also if you have made any modifications to the trucks air intake or exhaust your truck would require a proper a/f ratio tune. After cleaning my maf and throttle body, iac I relearned the ecu. It has learned over time to operate dirty. You want it to realize everything is clean so it can adjust back to proper operation.

I think the items you've listed are all the "go-to" solutions that myself, and others who've posted having this particular CEL code, have all tried first, and anyone here with the issues should try as well: the quick & easy stuff, clean/replace MAF, etc, as above from Jakeepoo

It seems that for the moment, my CEL problems have been resolved by adding the "aFe Power 51-82502 - Magnum FORCE Stage-2 Si Pro DRY S Intake System"

Time will tell, as the miles rack up, if the "fix" was a real fix. I did not reset the ECU after adding the intake. That way I can see if the corrections return down to normal, rather than have to relearn the fuel corrections from scratch. It took 2 months to relearn all the fuel trims last time the ECU was reset (it drove "normal-ish" for 2 months, then got the CEL codes again). Adding the aFe intake made an immediate difference without resetting the ECU.

I'm not telling everyone with the CEL codes P0175 & P0172 to run out and get an aftermarket intake. But since everyone else contributing here is talking about intake air box issues, and I could not see any problem with my intake, I just replaced it and it seems the problem has gone away.

It was an act of desperation.

I'll report back in a while with an update and/or if the CELs return.

Long road you have gone down to get this resolved. AFE makes awesome filters, I have been running one for 3 years now with out issue, Keep us posted for sure.

Keros, still going good with the intake? I'm about to just try that and see if it will be my miracle fix as well. Still having issues to this day and just hardly drive the truck anymore because of it.

I'm just as surprised as you are... she's still going strong, no problems. Even with the dramatic weather changes, and I have no doubts if there were problems the big swings in air density and humidity probably would have brought them out. But nope, she still runs like a champ.

To be honest, the roar the aFe gives the truck combined with how the floorboards now vibrate under high load at high RPM is a tad... scary... I know this thing does not stop or steer fast enough for the rate at which it can now pick up speed.

If someone had told me in June getting an aFe aftermarket intake would solve the problem, I'd have laughed at them. By August, it was an act of desperation.

By no means do I, or could I, possibly guarantee it'll fix your situation, BoostinZX, but I REALLY hope it does.

For the money, it's worth a stab.

At this point, I'm kind of desperate as well to have a reliable backup vehicle, so I'm sold, lol... hopefully you are getting a cut of the sales Did you purchase direct from aFe?

I bought mine from an aFe dealer listed off their website, TDOT Performance, in Canada.

For better or for worse, it took forever to ship. I ordered it mid July and it arrived Sept 8th.

They didn't make it sound like it was a special order thing until after the purchase... oh well. It all worked out.

When you say a "aFe intake" are you referring to a actual replacement intake manifold or their "Cold Air Intake System" ?

Seems like a trick question... would those be the same thing?

Eh, regardless, I'm referring to this:
Magnum FORCE Stage-2 Si Cold Air Intake System w/Pro DRY S Filter Media | aFe POWER

It replaces the entire airbox system up to the throttle body.

Nope wasn't a trick question, the intake manifold is connected to the heads and the throttle box is connect to it, I just wanted to clarify what you meant by "intake", thanks for the clarification.

haha, I get what you mean.

I'm an idiot...

I am in the same boat. About to give up on my truck I have had for 8 years.

Still going strong?

Did you ever end up buying it? Did it work out?