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Discussion Starter · #1 ·
I will start off saying that I love my little white Chevy Colorado "Pick em up Truck". Just turned 100K with no issues except a dealer replaced exhaust gasket at 20K. Damn thing sounded like a weed wacker!. Coming back from a 400 mil. run from Paso Robles a few weeks ago. The check engine light came on half way back and my repair guy tells me it is the Nox sensor 1. It will take a week and $500 to replace it. Two days later the check engine light turned off and my mechanic had not ordered the new sensor. Made a weekend run to Tahoe in the snow and the truck is running fine, no check engine light, except I normally average 24.8 mph, now I am averaging 29 mpg. I have no idea when the truck goes thru a a regen cycle. Do I run down and get a new sensor? Does the sensor play a part in the regen. process? If the sensor was out wouldn't the check engine light be one. Final why the increase in gas mileage?
 

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At 100k, I'd go ahead and replace both NOX sensors if you can find them (I think I found them on rock auto . They usually fail at about 50K (at least mine did).

If you are willing and a bit handy, you can replace the sensor yourself in about an hour or less . You just need a can of penetrant, a pack of antisieze, an O2 sensor socket (rentable from a parts store for free) , a ratchet and of course the actual sensor .. which is not that expensive . Way cheaper than $500.
I think I replaced mine from above ...

Also, I wouldn't throw away the old sensors. I'd try and clean them and store them as emergency spares in case the new ones ever go bad
 

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At 100k, I'd go ahead and replace both NOX sensors if you can find them (I think I found them on rock auto . They usually fail at about 50K (at least mine did).

If you are willing and a bit handy, you can replace the sensor yourself in about an hour or less . You just need a can of penetrant, a pack of antisieze, an O2 sensor socket (rentable from a parts store for free) , a ratchet and of course the actual sensor .. which is not that expensive . Way cheaper than $500.
I think I replaced mine from above ...

Also, I wouldn't throw away the old sensors. I'd try and clean them and store them as emergency spares in case the new ones ever go bad
Sage advice! Since most of my mechanical aptitude is with my 71 Blazer, I am still unclear about how to tell if the sensor is bad? Wouldn't the computer register if it failed?
 

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Sage advice! Since most of my mechanical aptitude is with my 71 Blazer, I am still unclear about how to tell if the sensor is bad? Wouldn't the computer register if it failed?
With that many miles I would replace both of them. They actually provide the reference on how much DEF fluid to inject to lower NOx to pre determined levels and have nothing to do with the REGEN of the DPF.

The only way to tell for sure if the truck is in regen is with some type of OBDii reader. However, if you're watching your instant mileage and you travel a typical route ,and, lets say your MPG on the dash is 28 mpg and that's the norm and all the sudden it drops down 5 to 8 mpg that would be an indication it's doing a regen. After about 20 minutes the mileage will jump back to the 28 when it's finished.
 

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100k miles-- I would order NOX 1 right now and be thinking ahead by ordering NOX 2 as soon as you can, just so you have them. I recently purchased both from Rock Auto and everything went great.

If the sensor is bad, or failing, it’s very possible that you will not have a CEL and corresponding code. To know for sure in the absence of a code, you would need a bi-directional scan tool that shows the real time readings of the sensors. If you are at 100k miles, in my opinion, they are already failing so do yourself a favor and just lean forward into changing them.

To change NOX 1, you need a 22mm (7/8) and 10mm socket or wrench. I use a small torch and breaker bar to help break the nut loose. I don’t use a NOX socket because I don’t save bad NOX sensors.

Sometimes, depending on other factors and what else may be happening with your truck specifically, you may need to reprogram a new NOX sensor. You may have to go to a dealer for this purpose depending on the diagnostic equipment you have at home. At least it will be much cheaper since you’re not paying them for the parts and labor to change it out.
 

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100k miles-- I would order NOX 1 right now and be thinking ahead by ordering NOX 2 as soon as you can, just so you have them. I recently purchased both from Rock Auto and everything went great.

If the sensor is bad, or failing, it’s very possible that you will not have a CEL and corresponding code. To know for sure in the absence of a code, you would need a bi-directional scan tool that shows the real time readings of the sensors. If you are at 100k miles, in my opinion, they are already failing so do yourself a favor and just lean forward into changing them.

To change NOX 1, you need a 22mm (7/8) and 10mm socket or wrench. I use a small torch and breaker bar to help break the nut loose. I don’t use a NOX socket because I don’t save bad NOX sensors.

Sometimes, depending on other factors and what else may be happening with your truck specifically, you may need to reprogram a new NOX sensor. You may have to go to a dealer for this purpose depending on the diagnostic equipment you have at home. At least it will be much cheaper since you’re not paying them for the parts and labor to change it out.
I didn't need to program anything when I replaced my NOX sensor 1 .

In the case of when my NOX sensor 2 went marginally bad, my DEF line heater also burnt out around the same time and the resulting clusterf***, even after replacing both parts could only be cleared by running a service bay regen. In hindsight I could have ran those procedures using the gretio app and my OBD MX Bluetooth scan tool but the dealer was the one who figured out the issue so I let them take care of the tests as the vehicle was under warranty at the time

In short, you shouldn't need to reprogram anything unless you have a complex issue like I did.
 
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