P0442 MIL

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wsteele

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We got up early and drove up into the hills to one of our favorite trails. This trail is about 7 miles total in a loop and we like it on weekends as we rarely see more than a few people on a whole hike. We must have passed 50 people at least. Wow, big holiday weekend, everybody was out. Helps to have perfect weather too, I guess.

When I started the Yukon up to turn around on the fire road at the trail head. I noticed a CEL didn't go out. My first thought was "Crud, one of those new O2 sensors I just put in was bad!", then I thought, "or worse, that Bank 2 Sensor 1 connector was such a bear to reach, I must have not gotten it back together correctly!".

I pulled out my handy dandy ODBII reader and plugged it in. I launched the app on my phone and started looking at what was going on. My wife asked what I was doing and I told her we have a check engine light and I wanted to know what I did wrong when I installed those new O2 sensors.

I checked the live data and everything seemed good on the O2 sensor and fuel trim front. I then did a code read and saw a P0442 code was set. I told my wife the CEL was on because I probably forgot to tighten the gas cap when I last got gas. I went back and sure enough, had a loose cap.

She was pretty impressed to have a device that could tell you your gas cap was loose. :)
 

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Well, the code was related to a small leak in the evap system and is likely a loose gas cap or is the first thing to check at least. It does not TELL YOU the gas cap is loose. It is nice to know that you can pull info like that when you need to.
 
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wsteele

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Well, the code was related to a small leak in the evap system and is likely a loose gas cap or is the first thing to check at least. It does not TELL YOU the gas cap is loose. It is nice to know that you can pull info like that when you need to.

Yeah, except the part where I was driving along looking at my iPhone. Luckily, it was a Forest Service road, no mounties around. :)

I also got to use my new Tech 2 to reset everything. Worked great. I also was waiting to get down pretty low on fuel, so I could refuel at the "no Ethanol" Mobil station down the road from my house. After I tanked up, I reset my Ethanol content (also with my Tech 2).

Now if I could figure out why my PCM always thinks there is an ever increasing Ethanol content in my gas. When I reset it this time, it was at 36% and open loop was getting kind of smelly.
 

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Yeah, except the part where I was driving along looking at my iPhone. Luckily, it was a Forest Service road, no mounties around. :)

I also got to use my new Tech 2 to reset everything. Worked great. I also was waiting to get down pretty low on fuel, so I could refuel at the "no Ethanol" Mobil station down the road from my house. After I tanked up, I reset my Ethanol content (also with my Tech 2).

Now if I could figure out why my PCM always thinks there is an ever increasing Ethanol content in my gas. When I reset it this time, it was at 36% and open loop was getting kind of smelly.

I wonder if there is a new calibration for the ethanol composition calculation. I'm not sure on the NNBS and reading calibrations, but can you use the Tech 2 SPS to download what calibrations are in it, and compare that using TIS2web?

EDIT: you can check for all available calibrations here using your VIN. Each calibration has a description of what issue it corrects.
https://tis2web.service.gm.com/tis2web/
 
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I also was waiting to get down pretty low on fuel, so I could refuel at the "no Ethanol" Mobil station down the road from my house. After I tanked up, I reset my Ethanol content (also with my Tech 2).

I'm doing the opposite tomorrow. My ethanol is at 9% right now and I'm taking my neighbors to the airport tomorrow, running the gas down a bit. Then on the way home I'm topping off with E85. I should have enough miles after that to get home and it should be reset by then. Curious to see what the % gets to.
 
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wsteele

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I wonder if there is a new calibration for the ethanol composition calculation. I'm not sure on the NNBS and reading calibrations, but can you use the Tech 2 SPS to download what calibrations are in it, and compare that using TIS2web?

EDIT: you can check for all available calibrations here using your VIN. Each calibration has a description of what issue it corrects.
https://tis2web.service.gm.com/tis2web/

Thank you very much. I will check it out tomorrow. I bet I am down rev.
 
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wsteele

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I wonder if there is a new calibration for the ethanol composition calculation. I'm not sure on the NNBS and reading calibrations, but can you use the Tech 2 SPS to download what calibrations are in it, and compare that using TIS2web?

EDIT: you can check for all available calibrations here using your VIN. Each calibration has a description of what issue it corrects.
https://tis2web.service.gm.com/tis2web/

Just found this for my VIN: 12614088 00000F82 - New software to ensure proper ethanol content calculation.

If I have this update, will it show when I pull up the SPS pages on my Tech 2?

Thanks again.
 

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Just found this for my VIN: 12614088 00000F82 - New software to ensure proper ethanol content calculation.

If I have this update, will it show when I pull up the SPS pages on my Tech 2?

Thanks again.

I don't think it will show on the Tech 2, at least it doesn't on my NBS. It might, though, so poke around a bit. I think all mine did was download the current numbers to the Tech 2, and I had to be running the Tech 2 in TIS2000 with the PC to see what the current calibration actually is. You'd probably have to run TIS2web for NNBS.
 
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wsteele

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I don't think it will show on the Tech 2, at least it doesn't on my NBS. It might, though, so poke around a bit. I think all mine did was download the current numbers to the Tech 2, and I had to be running the Tech 2 in TIS2000 with the PC to see what the current calibration actually is. You'd probably have to run TIS2web for NNBS.

I stole some time from the family and went out and fired it up. I used the SPS page and did the "Request Info" and along with the VIN, it returned a bunch of P/N's, one of which was that Ethanol calibration fix.

I don't know enough about the Tech 2 to know what I am looking at. :(

When I have more time, I will bang around some more and see if I can figure it out. I don't even know what sensors are used by the PCM to calculate Ethanol content. My assumption is it uses the percentage of Ethanol stored as a starting point for open loop and then uses closed loop trims to update the content percentage over time. But that is just a wild ass guess.
 

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I stole some time from the family and went out and fired it up. I used the SPS page and did the "Request Info" and along with the VIN, it returned a bunch of P/N's, of which was that Ethanol calibration fix.

I don't know enough about the Tech 2 to know what I am looking at. :(

When I have more time, I will bang around some more and see if I can figure it out. I don't even know what sensors are used by the PCN to calculate Ethanol content. My assumption is it uses the percentage of Ethanol stored as a starting point for open loop and then uses closed loop trims to update the content percentage over time. But that is just a wild ass guess.

So that list that it showed after you did the "Request Info" thing is the current calibrations in the truck.
 

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