# New CEL issue



## MOTO13 (Mar 26, 2014)

My car developed a CEL Monday immediately after start up. I went to Chevy today and they diagnosed it. Apparently there are 2 sensors of some kind that monitor the exhaust or are on the exhaust. The sensors are what I was told by the Tech as a part that is "RESTRICTED". Meaning the part is not an off the shelf part like an O2 or NOX sensor and can only be obtained directly from the GM factory when the specific issue requires this to be replaced. There are 2 of these sensors and the only way to tell which one is bad is testing when the car is cold...not at normal operating temp. They are going to look at the car again in the morning when the car is cold to determine which one it is. They can't simply order both apparently and be done with it. GM won't allow this. Does anyone know WTF is going on here?


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## revjpeterson (Oct 2, 2013)

Standard procedure for any emissions problems on the Diesel. They have to go through GM Technical Assistance to ensure they followed proper procedure before they will be given the parts. It has been the same in the past for the NOX and O2 sensors as well, so if those are now available without going through TAC, that's a new development. This has two purposes: 1. so they ensure a proper diagnosis and prevent dealers with limited experience on this system (since there were only 10,000 built in 2014, and only a few thousand 2015s so far) will not just throw parts at it. 2. to develop a central knowledge base of problems and solutions on the Diesel so that the collective experience of all dealer service departments can be disseminated to individual dealers for a given issue. 

In the end, it's a beneficial thing, and it shouldn't be much of an inconvenience if your dealer navigates the process correctly. When I had my O2/EGR code and service, my diagnosis, part acquisition, and repair were all complete in less than 72 hours, and the dealer gave me a vehicle to drive while the worked on it.


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## Scott M. (Apr 23, 2013)

Hopefully they will give you a free loaner car. Hopefully you will get the part fast. I have waited 2 weeks for a particulate matter sensor. On the bright side. sensor problems seem to be getting more rare on the forum. Maybe GM is making adjustments.


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## MOTO13 (Mar 26, 2014)

Oh...well if it is normal to restrict parts, I feel better. The tech stated it was not an O2 or NOX though, so I have no idea what is going on. They were out of loaners today. I had to drive my truck to work anyway but they are supposed to provide one tonight.


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## revjpeterson (Oct 2, 2013)

Could be an EGT (Exhaust Gas Temperature) sensor, but with the description about it being a pair of sensors that work together, it sounds more likely to be a Differential Pressure Sensor. Basically one measures the pressure inside the exhaust before the DPF, the other measures the exhaust pressure after the DPF. The pressure differential equates to the number of grams of soot collected in the DPF. When that reaches a certain threshold, it triggers a re-gen to burn off the soot and bring the pressure differential back to a certain spec.


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## MOTO13 (Mar 26, 2014)

The tech mentioned something about re-gen now that you mention it. Is this a big deal install wise?


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## Scott M. (Apr 23, 2013)

Not a really big deal but this would be the first differential pressure switch I have read about on this forum. EGT sensors are a more common failure. There is one on each side of the DPF.


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## MOTO13 (Mar 26, 2014)

I'll keep you guys posted.


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## diesel (Jun 8, 2013)

Sounds like the one CEL I had. There are a couple different exhaust gas temperature sensors and one code could mean either sensor was bad. They replaced #2 and it has been fine ever since.


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## MOTO13 (Mar 26, 2014)

This is what is scaring me about this car...expensive sensors that fail. Under warranty is one thing...inconvenient for sure, but at least no out of pocket $$. Out of warranty in a few years is a whole different ball of wax. These sensors and the diagnostics just to determine a problem can't be cheap. I know one thing, if I have any more issues I have to give serious thought about keeping this car.


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## revjpeterson (Oct 2, 2013)

MOTO13 said:


> This is what is scaring me about this car...expensive sensors that fail. Under warranty is one thing...inconvenient for sure, but at least no out of pocket $$. Out of warranty in a few years is a whole different ball of wax. These sensors and the diagnostics just to determine a problem can't be cheap. I know one thing, if I have any more issues I have to give serious thought about keeping this car.


Looks like the pressure sensors are the cheapest, at around $25, EGT sensors at around $50 and O2 sensors at $105, so overall not bad, with half being accessible easily under the hood using just an oxygen sensor socket or a basic open-end wrench. The other half appear to be easily accessible with a jack and the same tools from underneath the vehicle. The NOX sensors look a little more pricy at $244, but still easy replacements, so it shouldn't be necessary to pay labor if you can locate the sensor on a diagram, open the hood or crawl under the car, and turn a wrench. With a bluetooth code reader from Ebay for $15 and the torque app downloaded for your smartphone for less than $5, you can pull the codes yourself to identify the sensor in most cases.

If someone manages to accomplish programming the emissions delete for the ECU and you don't live in an inspection state, that could also become an option for many once the vehicle is out of warranty. If I'm faced with the choice of paying a few hundred for the delete or a couple thousand to replace major emissions components, I know which one I'll be going with.


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## MOTO13 (Mar 26, 2014)

It would be an easy decision if I didn't like the car...but it's a great car....except for these sensor issues. I am curious to what is wrong and what it would cost out of warranty.


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## diesel (Jun 8, 2013)

I am going to leave everything stock in mine. I am very curious how long everything will last.


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## RIXSTER (Apr 13, 2015)

No matter the car you have or will get, there is always going to be issues that COULD mean diagnostic fee or other general costs so keep that in mind, or keep trading off cars when the warranty expires.


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## MOTO13 (Mar 26, 2014)

Just got the call, it's some temp sensor on the exhaust or some crap. Need to order it. It would be approx. $80 for the part. Picking it up Tuesday and will give the part #. Apparently it is OK to drive as is and install the part when it arrives.


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## KpaxFAQ (Sep 1, 2013)

Thing is replacing sensors is easy, knowing what's wrong seems to be a bit more tricky. They aren't cheap so you don't want to throw parts at it.


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## MOTO13 (Mar 26, 2014)

This is precisely what worries me after the warranty is over. Does anyone know for sure what the warranty is regarding the sensors n the engine/exhaust? I've been given conflicting stories.


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## diesel (Jun 8, 2013)

MOTO13 said:


> This is precisely what worries me after the warranty is over. Does anyone know for sure what the warranty is regarding the sensors n the engine/exhaust? I've been given conflicting stories.


I can confirm my exhaust gas sensor was replaced under warranty at 61K miles. I believe it was under the federal emissions warranty.


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## oilburner (Jun 13, 2013)

diesel said:


> Sounds like the one CEL I had. There are a couple different exhaust gas temperature sensors and one code could mean either sensor was bad. They replaced #2 and it has been fine ever since.


there is actually 3 exhaust temp sensors, if the tech was correct saying 2 of, then I go with the dpf pressure sensors. in almost 2 years only had one issue an it was exhaust temp sensor #2.


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## MOTO13 (Mar 26, 2014)

What I don't get is that these sensors are there to tell you when there is a problem. It seems they are causing problems...at least for me and many others. One year old and 2 different sensors failing isn't a good track record. GM won't do crap to change the quality... you know this for sure. Look at the ignition problem they had for years and did nothing about. People died from it. I don't put much faith they will look into a sensor issue or two.


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## money_man (Feb 25, 2014)

My car is 14 months old (since I bought it). It's 16 months old if you go by the build date. I've yet to have any problems. 


Sent from the sexy electrician


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## diesel (Jun 8, 2013)

Seem to be a pattern with EGT #2


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## Classy56 (Jul 16, 2014)

Mine's in the shop now at 18k miles with a P20E2 code "EGT 1/2 correlation" or something like that.


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## diesel (Jun 8, 2013)

I wonder if the EGT #2 sensor that was used for replacement is an updated version. Mine went out at 61K miles and it won't be too long before I hit 122K.


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## Gator (Jul 14, 2013)

like that 100000 mile badge. 30000 more to go Diesel. how long you going to test that timing belt before changing it.????


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## diesel (Jun 8, 2013)

Gator said:


> like that 100000 mile badge. 30000 more to go Diesel. how long you going to test that timing belt before changing it.????


Probably 150K. Based on my calculations, it would be safe to go about 180K (with my driving habits, of course)


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## MOTO13 (Mar 26, 2014)

It was an EGT sensor...#2.


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## Classy56 (Jul 16, 2014)

MOTO13 said:


> It was an EGT sensor...#2.


 Mine too. Got it back yesterday.


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## MOTO13 (Mar 26, 2014)

You had one also? Yeah, it's my second sensor issue in a year and to be honest, I was tempted to just say eff it and start looking for something else. Don't need the headache and worry about the "what sensor next" crap. But the car was completed yesterday and I turned in the 2015 Traverse they loaned me. Note to self...don't buy a Traverse. Not impressed at all with this thing. Then I looked at the MPG...18. Not quite the 47 I'm used to. Anyway, I picked up the CTD and drove it the 3 miles home and realized again, just how nice the car really is.


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## diesel (Jun 8, 2013)

We have several votes for EGT#2. That was my one and only sensor problem in 113K miles.


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