P0442 MIL

[wsteele]

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.

 

[OR VietVet]

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.

 

[wsteele]

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.

 

[Fless]

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/

 

[Fless]

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.

 

[wsteele]

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.

 

[wsteele]

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.

 

[Fless]

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.

 

[wsteele]

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.

 

[Fless]

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.

 

[wsteele]

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

It shows the “P/N” but doesn’t show the version. Do they have more than one version for a P/N (calibration)?

 

[Fless]

It shows the “P/N” but doesn’t show the version. Do they have more than one version for a P/N (calibration)?

As much as I know, each 8-digit calibration number is unique. When I'm in TIS2000 for my NBS all I see are those numbers to choose.

 

[wsteele]

As much as I know, each 8-digit calibration number is unique. When I'm in TIS2000 for my NBS all I see are those numbers to choose.

As best I can tell from what the Tech 2 shows when I do "Request Info" in the SPS section, I do have that P/N. It doesn't display a version number like the VIN search returned, so I guess I do have the latest revision number update for the Ethanol calibration.

I don't buy E85 anymore, so the most I am getting certain times of the year is a maximum of 15%. I will wait till it starts reporting into the 30%+ Ethanol content range again and maybe take it in to the dealer and see what they say.

The good news is I can reset it when I need to, so it isn't a big deal either way.

 

[Fless]

Did you go to the site I listed to see if there were any further calibrations?

 

[wsteele]

Did you go to the site I listed to see if there were any further calibrations?

Yes, that is where I got the P/N. Mine has that as the last ECU update. What I was fuzzy on was the version number. The site lists a version number for the P/N but my Tech 2 only lists the P/N when I do the Request. But it does list that “P/N” as installed on my ECU.

 

[Fless]

This guy recommends resetting the LT fuel trims, too, after zeroing the fuel composition.

 

[wsteele]

This guy recommends resetting the LT fuel trims, too, after zeroing the fuel composition.

Good idea.

I think I figured out where my confusion is on the version number. It isn’t a version number, it is a verification number, which I assume is a form of checksum, so the “P/N” is the new calibration.

The one I have is the last one for my VIN, so I got the latest and greatest.

I will reset the L/T trims and see what happens. They were already trending down yesterday as my S/T trims were really close to zero.


Maybe resetting to a baseline Ethanol, using that Ethanol free Mobil gas and resetting the long term trims will teach my ECU to stop recalibration above the normal 10% or so, I usually have in the tank.

 

[Fless]

I'd be curious to know how it goes. Mine has the actual sensor so it's a bit different system.

 

[kbuskill]

Good idea.

I think I figured out where my confusion is on the version number. It isn’t a version number, it is a verification number, which I assume is a form of checksum, so the “P/N” is the new calibration.

The one I have is the last one for my VIN, so I got the latest and greatest.

I will reset the L/T trims and see what happens. They were already trending down yesterday as my S/T trims were really close to zero.


Maybe resetting to a baseline Ethanol, using that Ethanol free Mobil gas and resetting the long term trims will teach my ECU to stop recalibration above the normal 10% or so, I usually have in the tank.

It is funny that this subject is being brought up now as my truck is doing the same thing.

I ran E85 for several tanks months ago and then went back to my normal 89 octane which is only supposed to have 10% ethanol max.

I checked my ethanol % the other day and it was showing up in the 30 something % range.

I reset the ethanol content (which makes it read 3%) and fuel trims the other day and drove around for a while. After refueling the truck and driving it settled in at 24% ethanol.

Yesterday I reset just the Ethanol % and drove around while watching the ST and LT fuel trims.

Then I went and topped off the tank (from a half a tank) with 89 Ethanol free. After the ethanol recalibrated it settled at 17%.

I am still not happy.

I have been reading everything I can find about it and my plan is to clean my MAF sensor and top off again with Ethanol free and see where it ends up.

I replaced the upstream O2 sensors with Denso units about 2 years ago so I don't think they are an issue BUT I did notice the driver's side drops down a lot lower than the passenger side.

Passenger side bounces back and forth between 700-900 mv... drivers side does the same 700-900 mv but will drop down to 100-200 mv for a second and then back to normal. The 700-900 mv tells me it is running rich.

If cleaning the MAF sensor doesn't correct the issue then I may end up replacing the O2 sensors again.

The only on going issue i have is a CEL that comes on periodically for EVAP gross leak detected P0455.
I have replaced everything in the EVAP system minus the actual lines, tank, fuel pump.

Keep me posted on how you make out with yours.

 

[wsteele]

It is funny that this subject is being brought up now as my truck is doing the same thing.

I ran E85 for several tanks months ago and then went back to my normal 89 octane which is only supposed to have 10% ethanol max.

I checked my ethanol % the other day and it was showing up in the 30 something % range.

I reset the ethanol content (which makes it read 3%) and fuel trims the other day and drove around for a while. After refueling the truck and driving it settled in at 24% ethanol.

Yesterday I reset just the Ethanol % and drove around while watching the ST and LT fuel trims.

Then I went and topped off the tank (from a half a tank) with 89 Ethanol free. After the ethanol recalibrated it settled at 17%.

I am still not happy.

I have been reading everything I can find about it and my plan is to clean my MAF sensor and top off again with Ethanol free and see where it ends up.

I replaced the upstream O2 sensors with Denso units about 2 years ago so I don't think they are an issue BUT I did notice the driver's side drops down a lot lower than the passenger side.

Passenger side bounces back and forth between 700-900 mv... drivers side does the same 700-900 mv but will drop down to 100-200 mv for a second and then back to normal. The 700-900 mv tells me it is running rich.

If cleaning the MAF sensor doesn't correct the issue then I may end up replacing the O2 sensors again.

The only on going issue i have is a CEL that comes on periodically for EVAP gross leak detected P0455.
I have replaced everything in the EVAP system minus the actual lines, tank, fuel pump.

Keep me posted on how you make out with yours.

I will.

I did see in the clip @Fless posted the guy said to clean the MAF, along with resetting the trims. Makes sense, I will also do that as well.

My MAF might be dirty as I had forgotten to change air filters and when I changed it the other day, it was really bad. I have been on fire roads and 4X tracks a lot in the last few years, really dirty environments.

Also, I too changed my O2 sensors recently. I did get the OE units and they seem to be working fine (hopping way down and up).

I haven’t gotten any codes from this stuff, other than the code for the loose cap. If it pops back up, with the cap tight, I will report that as well.