# Bad NOX sensor...no parts in the worlddddd



## Bbruew (Jul 6, 2019)

My car went into the dealer on jan 12 regarding a CEL from a diesel emission code.(I forget the code). 4 days later they got my car in and said its a bad NOX sensor(I believe its the downstream one). Service writer calls me back and says, "Good news is that its under warranty, bad news is there are none in stock and I have no time frame one when they will be in stock again. So every week I get an update, "no parts still, they are looking." Well here we are 5 ish weeks later and still nothing. I filed a claim with GM who is looking into it and hopefully something will come of it soon... My car has 51k on it and its already had injectors replaced at 29k, glow plugs, and multiple TPMS sensors under warranty. Has anyone had issues like this where you are waiting over a month for a part? This just seems ridiculous.


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## CrushTD (Oct 4, 2020)

Only once, thankfully, but yes. I had a bad EGR cooler about a year ago and my car was in the shop for over a month while they were waiting for a part to come in. Not quite as bad, but during my last oil change at the dealer they ran out of diesel oil halfway through and had to go to another dealership to get more. That was a fun 2 hours in the waiting room.


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## Carminooch (Mar 23, 2018)

Don’t for a second believe them when they say they aren’t in stock. My car was in for over 2 months for a bad nox sensor so I milked them for a loaner car- in the fine print, driving my car knowing I have an issue voids my extended warranty I got from them. 

You would think using their loaner car as collateral would nudge them into finding the part.

2 months went by, nothing and no update. I called the dealerships in the surrounding area and quickly found it. The dealer near me said they would be happy to send the part over to where my car is.

My dealership said they wouldn’t initiate the transfer because it does something to their inventory or something. Personally I don’t care, they care more about their inventory than a customer.

I eventually made my GM senior customer advisor coax the dealership into doing what ever was needed to get the part from the other dealer and install it. Naturally they didn’t bother to tighten the heatshield down properly and left out bolts for a seemingly easy task to replace 1 sensor...

TLDR; call surrounding dealerships. They may have it. They can initiate a transfer and if your dealer pushes back due to inventory tracking reasons, partner with GM customer relations.


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## Carminooch (Mar 23, 2018)

CrushTD said:


> Only once, thankfully, but yes. I had a bad EGR cooler about a year ago and my car was in the shop for over a month while they were waiting for a part to come in. Not quite as bad, but during my last oil change at the dealer they ran out of diesel oil halfway through and had to go to another dealership to get more. That was a fun 2 hours in the waiting room.


So sorry to derail the discussion but-

How did you know you’re egr cooler was bad? I’ve had a persistent hesitation / bucking feeling on cold start that lasts 2 minutes and goes away immediately if the rpm’s are above 2k. No CEL, ever

Egr valve was blocked almost solid, made them clean it out under warranty. They refused to touch the cooler due to the amount of labor required so I’ve been dealing with this issue for almost 40k miles. It definitely got a little better after the valve was cleaned but only slightly.


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## Barry Allen (Apr 18, 2018)

CrushTD said:


> Only once, thankfully, but yes. I had a bad EGR cooler about a year ago and my car was in the shop for over a month while they were waiting for a part to come in. Not quite as bad, but during my last oil change at the dealer they ran out of diesel oil halfway through and had to go to another dealership to get more. That was a fun 2 hours in the waiting room.


Hah, they didn't check to see that they had the oil in stock BEFORE draining it from the engine?

Rookie mistake. I saw that years ago when working at Wal-mart. Told guys to get the oil from the stock room, count out the quarts, and make Gosh-darned sure they have the correct oil filter in their hands before they crush, mangle, puncture, and remove the old one.


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## Barry Allen (Apr 18, 2018)

Carminooch said:


> How did you know you’re egr cooler was bad?


In my car, the CEL came on with some emissions codes. The dealership said GM technical support at HQ told them to replace the cooler with an updated/corrected part. It took about 5 months to get the part in stock.


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## Barry Allen (Apr 18, 2018)

Carminooch said:


> You would think using their loaner car as collateral would nudge them into finding the part.


For warranty work, doesn't GM corporate cover the cost of the loaner? They dealership might not care if that's the case.


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## CrushTD (Oct 4, 2020)

Carminooch said:


> So sorry to derail the discussion but-
> 
> How did you know you’re egr cooler was bad? I’ve had a persistent hesitation / bucking feeling on cold start that lasts 2 minutes and goes away immediately if the rpm’s are above 2k. No CEL, ever
> 
> Egr valve was blocked almost solid, made them clean it out under warranty. They refused to touch the cooler due to the amount of labor required so I’ve been dealing with this issue for almost 40k miles. It definitely got a little better after the valve was cleaned but only slightly.





Barry Allen said:


> In my car, the CEL came on with some emissions codes. The dealership said GM technical support at HQ told them to replace the cooler with an updated/corrected part. It took about 5 months to get the part in stock.


Same. I had a CEL come on and the dealership diagnosed it.


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## CrushTD (Oct 4, 2020)

Barry Allen said:


> Hah, they didn't check to see that they had the oil in stock BEFORE draining it from the engine?
> 
> Rookie mistake. I saw that years ago when working at Wal-mart. Told guys to get the oil from the stock room, count out the quarts, and make Gosh-darned sure they have the correct oil filter in their hands before they crush, mangle, puncture, and remove the old one.


Haha no! The service advisor was a bit embarrassed when she came in and told me they ran out. I could actually see my car from the waiting area and started to get concerned when I saw the technicians leave it up on the lift and not go anywhere near it for about half an hour.


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## Barry Allen (Apr 18, 2018)

CrushTD said:


> Haha no! The service advisor was a bit embarrassed when she came in and told me they ran out. I could actually see my car from the waiting area and started to get concerned when I saw the technicians leave it up on the lift and not go anywhere near it for about half an hour.


I saw that a few times where I worked. It was often stuff with filters not being in stock and we've already removed, crushed, mutilated, etc. the prior filter. Luckily there were auto parts stores in town that we could send someone to get what we needed, but it was always embarrassing to happen.


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## oregon_rider (Jul 21, 2017)

I needed a dash part to correct a rattle that I had diagnosed just as my bumper to bumper warranty was about to expire. I have 27k miles but was rolling up to 36 months of ownership.

Three months.... This wasn't a diesel specific part - just a generic "body part". Since I am working from home - basically they stored the car for me during that time... I had my wife's car and my truck to drive...

I am guessing the delays and lack of parts stock is a combination of pandemic related supply chain issues _AND _ GM management not stocking anything to conserve cash until the economy turns around...

I stocked up on fuel filters, oil filters & cabin air filters a month or two after the pandemic reared it's ugly head...

jeff


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## Barry Allen (Apr 18, 2018)

oregon_rider said:


> I needed a dash part to correct a rattle that I had diagnosed just as my bumper to bumper warranty was about to expire. I have 27k miles but was rolling up to 36 months of ownership.
> 
> Three months.... This wasn't a diesel specific part - just a generic "body part". Since I am working from home - basically they stored the car for me during that time... I had my wife's car and my truck to drive...


Can't you drive the car? Once you get a warranty item verified by the dealership as having started or occurred prior to the time or mileage limit, I don't think driving the car more makes the repair something they won't cover.


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## oregon_rider (Jul 21, 2017)

Barry Allen said:


> Can't you drive the car? Once you get a warranty item verified by the dealership as having started or occurred prior to the time or mileage limit, I don't think driving the car more makes the repair something they won't cover.


 The warranty was on the edge of expiring. So the service adviser wanted to keep the service ticket open. The repair was completed 2-3 months after the warranty expired.

It was no big deal to me - I am not driving car much anyway because I started a new job where I am working from home full time. As I said, I have a spare truck I can drive - chevy duramax diesel (2005).

jeff


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## Barry Allen (Apr 18, 2018)

oregon_rider said:


> The warranty was on the edge of expiring. So the service adviser wanted to keep the service ticket open. The repair was completed 2-3 months after the warranty expired.


Yeah, as long as the issue was identified while the warranty was intact, it's valid.


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## Barry Allen (Apr 18, 2018)

Years ago a co-worker of mine had a Pontiac Firebird that had some sort of oil leak issue. When the warranty was 36,000 miles, it was a problem for him right about 35,800 miles. The dealership spent some time trying the "We can't duplicate the issue" game and urging him to try and bring it back when it was doing it again, yada yada. The whole thing was them basically trying to push a rear main seal job off past the warranty so they wouldn't have to cover it. "Oh, go ahead and drive it some more to see if it gets worse." Meanwhile, in about a week or so, he'd be driving it past the warranty expiration...


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## Bbruew (Jul 6, 2019)

Carminooch said:


> So sorry to derail the discussion but-
> 
> How did you know you’re egr cooler was bad? I’ve had a persistent hesitation / bucking feeling on cold start that lasts 2 minutes and goes away immediately if the rpm’s are above 2k. No CEL, ever
> 
> Egr valve was blocked almost solid, made them clean it out under warranty. They refused to touch the cooler due to the amount of labor required so I’ve been dealing with this issue for almost 40k miles. It definitely got a little better after the valve was cleaned but only slightly.


I have noticed this as well. No CEL


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## MRO1791 (Sep 2, 2016)

Bbruew said:


> My car went into the dealer on jan 12 regarding a CEL from a diesel emission code.(I forget the code). 4 days later they got my car in and said its a bad NOX sensor(I believe its the downstream one). Service writer calls me back and says, "Good news is that its under warranty, bad news is there are none in stock and I have no time frame one when they will be in stock again. So every week I get an update, "no parts still, they are looking." Well here we are 5 ish weeks later and still nothing. I filed a claim with GM who is looking into it and hopefully something will come of it soon... My car has 51k on it and its already had injectors replaced at 29k, glow plugs, and multiple TPMS sensors under warranty. Has anyone had issues like this where you are waiting over a month for a part? This just seems ridiculous.


Short answer: Yes, your experience waiting for parts is TYPICAL. In fact if you did not have a long wait for parts, that would be noteworthy. GM is horrible about parts these days, there is just no way to call it anything other than that. 

Technically, due to a gasket of all things, that they could not get for the EGR cooler on my 2017 I could have forced a buyback under the lemon law, the wait was much more than 5 weeks, and I put quite a few miles on the Malibu Loaner during that time! Other cars that were not stuck at the dealership I also had to wait for extensive time periods to get the parts in stock.


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## Bbruew (Jul 6, 2019)

Update: 8 1/2 weeks later I got a Nox sensor put in the car, Drove it 2 times and the code has just came back on (P20EE). So back to the dealership it goes. At what point can you claim lemon law? And yes I already have a claim in with GM and have been speaking with them every week.


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## TDCruze (Sep 26, 2014)

Bbruew said:


> Update: 8 1/2 weeks later I got a Nox sensor put in the car, Drove it 2 times and the code has just came back on (P20EE). So back to the dealership it goes. At what point can you claim lemon law? And yes I already have a claim in with GM and have been speaking with them every week.


That is extremely disappointing for sure. Is it possible they changed the wrong sensor?


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## Bbruew (Jul 6, 2019)

TDCruze said:


> That is extremely disappointing for sure. Is it possible they changed the wrong sensor?


I wouldn't think so, it said bank 1


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## Snipesy (Dec 7, 2015)

Bbruew said:


> Update: 8 1/2 weeks later I got a Nox sensor put in the car, Drove it 2 times and the code has just came back on (P20EE). So back to the dealership it goes. At what point can you claim lemon law? And yes I already have a claim in with GM and have been speaking with them every week.


It’s possible the SCR is just full of DEF crystals. This will set off the NOx sensor almost immediately.
Which is why we always do service regens when replacing sensors. It’s the easiest way to clean the SCR as well.

You can give them my number if they are having trouble with GM.


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## Snipesy (Dec 7, 2015)

Bbruew said:


> I wouldn't think so, it said bank 1


P20EE just means the measured NOx reduction isn’t as good as it should be. It’s a reading from BOTH NOx sensors.

Bank 1, 2, etc is just an annoying SAE term. I’d ignore it.


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## TDCruze (Sep 26, 2014)

There are 2 Nox sensors Bank 1 sensor 1 (upstream) and Bank 1 sensor 2 (downstream). The P20EE refers to a downstream sensor reading issue, but other things can cause this code besides a faulty sensor as well.


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## TDCruze (Sep 26, 2014)

Snipesy said:


> It’s possible the SCR is just full of DEF crystals. This will set off the NOx sensor almost immediately.


So, would this be caused by a leaking DEF injector typically?


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## Bbruew (Jul 6, 2019)

Snipesy said:


> It’s possible the SCR is just full of DEF crystals. This will set off the NOx sensor almost immediately.
> Which is why we always do service regens when replacing sensors. It’s the easiest way to clean the SCR as well.
> 
> You can give them my number if they are having trouble with GM.


SCR? Also if you would like to PM me your number I can give it as a refer to the dealership.


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## MP81 (Jul 20, 2015)

Selective Catalytic Reduction - it's where the DEF is injected to lower the levels of NOx emissions the engine produces - which is why there is a NOx sensor before and after it.


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## Snipesy (Dec 7, 2015)

TDCruze said:


> So, would this be caused by a leaking DEF injector typically?


It’s possible. But in my experience it’s just bad programming. Ammonia registers as NOx which complicates things when Ammonia slip is occurring.

If the service Regen doesn’t fix the issue then I would start looking at the def injector and pump. Possibly even the catalyst itself (but I have said this before, catalyst failure is somewhat rare at this mileage).


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