# Anyone have Part Number for NoX sensors for 2015 Gen 1 Cruse Diesel



## DslGate (Jun 29, 2016)

Got the dreaded Poor Quality Def message for about 40 miles and then it disappeared, BUT check engine light remained on. Took to stealership and was advised that I need 2 NoX sensors and that total was going to be $1,900 to replace them both. This is just for the NoX sensors, not including the $60 for oil change and $80 for fuel filter. The Def Tank was replaced at 51K miles about a year ago under the Special warranty and car now has 61K miles with no other issues than this recent Poor Quality Def Message. Anyone please help with the NoX sensor part #s and also locations. I know that #1 is on front near radiator and the other is where?? Any helps is appreciated. Note too that one of the NoX was replaced when I first got the car under warranty at about 15K miles.


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## pandrad61 (Jul 8, 2015)

If the repair was 10,000 miles ago it should be well within the warranty period. I will take it back and show them the invoices and make them replace it.


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## DslGate (Jun 29, 2016)

pandrad61 said:


> If the repair was 10,000 miles ago it should be well within the warranty period. I will take it back and show them the invoices and make them replace it.


They are saying it's NOT the DEF tank and that it's the NoX sensors. This is the codes they got:

P249D Closed loop inductant injector flow too low
P20EE: Nox catalytic efficiency below threshold
P249E: Nox Catalytic efficiency flow too high
P2BAA: Exhaust NoX converter HIGH, low reductant consumption

The interesting thing is, the car runs fine and the Def Poor Quality message disappeared, but CEL was still on??


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## Snipesy (Dec 7, 2015)

$1,900 to turn two screws and plug something in?


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## DslGate (Jun 29, 2016)

Snipesy said:


> $1,900 to turn two screws and plug something in?


Yeah @Snipesy, thanks  Highway robbery ; I found the part numbers and Amazon and Rock auto have them for about $400 for both. Anyone have any idea where # 2 is on the system? (downstream unit??)


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## MP81 (Jul 20, 2015)

The NOx 2 sensor is the second to last sensor in the system (the Particulate sensor being the last sensor) - both just forward of the rear tires. The module it is hardwired to, which also has to come out along with it, is mounted up near the fuel filter.

This is a good guide to use to replace the NOx 2, as it's the same procedure as the particulate sensor: How To: Replace Diesel Particulate Matter Sensor...

You may need a torch.


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## pandrad61 (Jul 8, 2015)

DslGate said:


> They are saying it's NOT the DEF tank and that it's the NoX sensors. This is the codes they got:
> 
> P249D Closed loop inductant injector flow too low
> P20EE: Nox catalytic efficiency below threshold
> ...


Is think it all be covered under the special warranty being this is all emissions. I’d contact GM directly


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## MP81 (Jul 20, 2015)

pandrad61 said:


> Is think it all be covered under the special warranty being this is all emissions. I’d contact GM directly


It almost sounds like the DEF injector itself, to me...


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## pandrad61 (Jul 8, 2015)

MP81 said:


> It almost sounds like the DEF injector itself, to me...


Exactly my thoughts. Still should be covered


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## Snipesy (Dec 7, 2015)

My approach is a service regen followed by a def fluid quality test.

Like 90% of the time it is NOx sensor 2. Remaining 10% is a tossup between the DEF Pump and NOx Sensor 1. 

Catalyst failure and def injector failure are definitely super rare. As in I have not seen them personally and when I have heard of them being replaced I believe it was due to an inexperienced diesel tech.

Also many times the def fluid quality test will pass, but I will replace the NOx sensor 2 anyway depending on the vehicle age.


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## Snipesy (Dec 7, 2015)

Also I will say any DTC, unless it is a circuit failure.... Call it indeterminate. P20EE for example is suppose to mean the catalyst is bad, but in reality it is almost always NOx sensor 2. Those flow rate errors may have just been accidentally flagged and there is in fact nothing wrong with the flow rate.


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## DslGate (Jun 29, 2016)

Snipesy said:


> My approach is a service regen followed by a def fluid quality test.
> 
> Like 90% of the time it is NOx sensor 2. Remaining 10% is a tossup between the DEF Pump and NOx Sensor 1.
> 
> ...


Didn't have the $1,900 work done and just gt the oil change and the fuel filter. They charged $160.00 for diagnostic time and since its a UNION shop, the book times are absolutely outrageous. They car ran great for about an hour and then the Reduced Power message arrived adn yes, power is redued for sure. Ordered the NoX1 sensor and am going to install this weekend. Hopefully, that's the $1,900 issue resolved. FWIW, The Nox1 and NoX2 talk in a loop (circuit) , so when one goes bad, it tells the ECU and gives the check engine light, even if the other sensor is still good.


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## MP81 (Jul 20, 2015)

Do you have Bi-Scan? Usually you can take a look at the PPM readings for the NOx sensors. I remember when the NOx2 sensor went out last on ours, it was reading something like ten times _higher_ than the NOx1 sensor.


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## DslGate (Jun 29, 2016)

MP81 said:


> Do you have Bi-Scan? Usually you can take a look at the PPM readings for the NOx sensors. I remember when the NOx2 sensor went out last on ours, it was reading something like ten times _higher_ than the NOx1 sensor.


Sorry mate for the late reply. The CEL finally went away all on its own. One day I started the car after sitting overnight and voila, no CEL. Just like that, CEL gone and car is running great despite our 22 degree F temperatures at night and in the morning (-6 celsius). It's truly an engima because if you scan it now, it shows NO faults or codes. NONE. Perhaps it took time to adjust to the new NoX1 sensor that I installed for $120 bucks. Who knows? When the car runs with no CEL, it runs great and can cruise all day long at 90 mph (145 kmph) and still get in the 40s mpg with low DEF usage. Like I said, an enigma.


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