Did it give you a CEL. I had a bad one that didn’t set off anything. Found it myself scanning. My understanding is these won’t throw you into limp mode. Could be wrong but think I read that.


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I am fighting an issue with Nox1, Nox2, and DEF Injector. I started with the P20EE code, but then got one for NOX1 and NOX2 values are all over the map. So far in talking with the dealer it seems that limp mode will be enabled when you can no longer properly regen. I only bought Dec 21 truck and it 's used a lot more def than either 2 LMLs did. I have a banks data monster coming due to CTS2 not showing enough data parameters and truck came with a Pedal Monster. I've been able to run a few service regens with either my scanner or the CTS2 to get the soot back down. I was at 90% soot in only 186 miles, some highway, but no towing. GM can't keep enough new NOX sensors in stock so you have to get on the waiting list and I was told it takes roughly 2-3 months to get them, but at least I'm on a list now. I also figued dealers will get stock before any cheaper sources unfortunately. #21 on the list at my dealer which is rural. This is a new manufacturer, I guess Continental couldn't get it right. The only sensors you can find online are made in China, I've talked to the guys at DMAXStore and they had compiled a list of all known numbers and I just searched them this weekend. So even though I don't know if I need both sensors right now due to the wait times I just ordered both to have on hand since I'm at 183K and I started having issues.

 

How's it going with the NOX sensors? We're playing the waiting game now. Our 2018 has been at the dealer for 4 weeks now and counting.

 

First, a regen has nothing to do with nox levels or def usage. Nox1 gets a reading, def injected, nox 2 gets a reading. If the nox2 reading is not low enough, more def is injected and if it can't keep nox 2 low enough it throws a code. Could be a nox sensor out of calibration, or bad def, or bad def injection system.

You can get a limp for nox reduction system too. But it normally gives a countdown first.

Tooling around town, with a couple cooldown cycles and I only get around 186 miles between regens. More soot is produced with cold engine, stops and starts, more NOX is produced with hot engine.

 

Nox sensors do affect def injection, the amount of def injected varies based on readings between NOX1 and NOX2. If they aren't reading correctly it can cause more or less def to be injected which can then lead to other issues. This is what I was told by the service advisor. He's seen bad NOX sensors have no effect and he's seen it cause other issues, all depends on the truck somehow. I was giving background of what I've seen with my issues along with what I got from the dealer with regards to limp mode and regens. Just giving context in case it may help the OP or if he ends up getting the P20EE code which has been known to get thrown for bad def, bad def injector, bad nox sensors and maybe a couple other things. GM has also had at least 3 revisions of nox sensors and has had reprogamming and testing for nox sensor issues on this platform, just not on the 2018 model year from what I've been told.

From what I can tell a NOX sensor that is still somewhat working doesn't necessarily cause a limp mode, but if it gets worse or outright dies that would cause the whole truck to go down.

My around town regens started at 300-400 miles, while highway was 700ish unloaded. Now straight highway is 300-500, 600 miles over 8-9 hours going 65-75 except for a couple stops right off the highway while around town with some backroads/highway is 186. I live 15 min from town and it's at least 45mph for 5-10 min getting to town. I'm not driving around city day in and out. Regens don't affect NOX and DEF, but NOX and DEF affect soot loading which then affects regens.

 

From what I can tell the new revision is #4. It's a new manufacturer and they just can't keep up with the need at the moment is what my dealer told me. I'd like to know why they had to change from the lml sensors as those didn't have the failure rate of these on the L5P.

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I ordered both NOX sensors from findlayautoparts.com early this year. Had them at my door in one week.
Had a P20EE from a bad def injector. Replacing it and NOX2 sensor took care of the code.
2018 L5P with 130k miles.

 

Having same issues...how much were ur up and down stream sensors and def injector

 

Papi, you are lucky then. Must have gotten some older ones they had around or the shortage hadn't hit yet. Dealers can't even order ones to stock, all orders must have a VIN attached to be able to order them now.

 

2017+ can run indefinitely on a bad NOx sensor. But it depends on what the failure is and how badly the readings are off. I.e., any sort of circuit failure will immediately cause a countdown.

But just low performance (P20EE, etc...) no longer causes a countdown as of 2017+. That function is instead replaced by the DEF Quality Sensor.

There you go... Straight from the horse's mouth.

 

coyote, there was already a shortage of nox sensors when I ordered mine. They must have got new stock. I was expecting to wait a couple of months.

 

Had P20EE at 6,000 miles on my 22 L5P. Took to dealer today and they said both sensors working fine and did a relearn. Driving from FL to NY tomorrow, hope I don't have any issues with it.

 

I have a nox 2 problem. I purhcased a replacement part but the new parts nipple within the unit is on the wrong side so the male won't slip into the female. anyone else been having this issue?

 

actually the sensors do, if the sensors are bad the engine will run rich, the mileage will drop, and soot level rises, hence more Regeneration, the sensor's should be replaced in pairs, they are different but look the same, do not use off brand's just OEM, as they are not fun to change

 

This makes me sick.
ive got a 19 L5P with 38000 miles it’s now six weeks at dealer awaiting a nox sensor.
per GM customer care senior advisor “ when it manufactured and shipped they’ll advise“
Then to dealer then install it.
WTF are they kidding? This is prevalent problem should be a recall