P2099

[scth]

700 miles into driving from California to Florida. Got a CEL. Reader says P2099. Running rich on bank 2 post catalytic. Trying to see if we can keep the schedule or if stopping at a dealer would be better. ‘16 XL Denali - 37,000 miles. All dealers closed right now. Anyone seen this one? O2 sensor on right side looks fine, not loose, no wire chafing that I can see. Any suggestions?

Thanks!

 

[kbuskill]

700 miles into driving from California to Florida. Got a CEL. Reader says P2099. Running rich on bank 2 post catalytic. Trying to see if we can keep the schedule or if stopping at a dealer would be better. ‘16 XL Denali - 37,000 miles. All dealers closed right now. Anyone seen this one? O2 sensor on right side looks fine, not loose, no wire chafing that I can see. Any suggestions?

Thanks!

Not sure but 2016 should be in the K2 section of the forum...

@NathanJax can you fix it for him.

 

[wjburken]

Are you seeing any difference in engine performance?

 

[scth]

Are you seeing any difference in engine performance?

No change. Smooth idle. Haven’t noticed a change in mpg.
My theory is the high temps +110° F and altitude +4,000’ is just too much for the computer to keep up with? Not trimming the fuel enough so it shows rich? Not sure. I’m a wanna be mechanic.

Thanks!

 

[scth]

OK - felt ballsy. Erased the CEL. Drove another 700 miles, no issues. Temps today a minimum of 13 degrees cooler and elevation dropped 2,000’ so maybe my theory was close to the truth. Who knows. Thanks.

 

[CrashTestDummy]

Since the OP noted that his Denali 'self-healed', I'll bring this thread back up from the dead. While literally driving the Tahoe to get it inspected, the CEL came on. Checking for codes, it's a P2099. I did a visual inspection of the wiring for the trailing O2 sensors, and all looks good. Although it was fully-seated, I unplugged and reconnected the MAF connector. The connector blades were straight and clean. The battery terminals are clean and. tight.

The last thing we did to this. truck was replace the water pump. I did pull the Air Raid tube off to get better access, but checked the connections for it, and they are good. I'm seeing no evidence of any rodent activity under the hood. The truck runs fine, no stumbles, no rough idle, no problems.

Unless someone here has practical experience with this, I'll head to the dealer tomorrow and pick up a new O2 sensor to throw on it. I'm open to any suggestions, though. Thanks.

It's like this think KNOWS we're going for inspections!!

 

[swathdiver]

 

[CrashTestDummy]

Went for a drive while monitoring the O2 sensor voltages. The trailing sensors were both running in. the 0.6-0.8V range, tracking similar values on both sides. Speeds were low, less than about 40, but I did do a couple of 'spirited' acceleration runs to that speed. Still similar readings both sides.

 

[91RS]

Start with both OEM pre-cat oxygen sensors and if it comes back it will need that bank of injectors.

 

[CrashTestDummy]

But the DTC is for the post-cat O2 sensors!

 

[91RS]

No, it isn’t. The code isn’t technically for oxygen sensors at all, but it is almost always caused by a very slightly skewed reading from one of the pre-cat sensors making the fuel trim incorrect at certain times. It’s a good idea to replace both at the same time when that happens to make sure they’re both reading accurately.

 

[Fless]

Dig a little deeper and tell us what your fuel trims look like, both at hot idle and at about 1800 rpm.

On your scanner look at the Freeze Frame data to see if anything sticks out.

Although not for your year vehicle, the link below has a bit more info on the code and why it sets. Note the typical causes.

P2099 — 2013 Chevrolet Tahoe 2WD V8-5.3L Service Manual | Operation CHARM

Detailed repair manual for the 2013 Chevrolet Tahoe 2WD V8-5.3L.

charm.li

 

[CrashTestDummy]

Here are the hot idle and ~1800 RPM fuel trims:

 

[CrashTestDummy]

And here is the freeze frame output:

I usually don't look at this stuff unless there's a problem. The only thing that really stands out to me, though, is the IAT bank1 and 2 sensor temps. It was a toasty-warm summer day in Houston, yet IATs are at 32-deg F. Possible bad MAF??

 

[CrashTestDummy]

And just like that, -> P O O F !!<-, it's off!! Ran to the inspection station and got the truck to pass. The wonder of these self-healing DTCs!!!!!