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So after this new ECM program recall that I had a couple weeks ago I have had 3 codes pop up. Two of them I cleared last week and haven’t seen again and now this one. I called Chevy and they told me that it is pointing to a clogged vent valve on the fuel tank. Does anyone else Have this issue and know of a fix and how to unclog the vent?

Thanks in advance!

- Chris
 

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I had P0101 and P026D, my dealer told me that my injection pump had failed. It was still driving, but pressures were low. I had not had the recall done yet. Since then, another friend with an 18 had the same two codes within a week of mine. Hoping they were right, but I'll tell you after the injection pump or recall my truck has WAY more HP.
 

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I have a 2017 L5P with 112,000 miles on it. I have extended warranty until 120k. I have had my truck at dealership for one week looking in to my P026D trouble code. They have no idea so they stated on paper work they were going to start with NOX sensor 1 and replace it. They did and 40 miles later same P026D code. I bought the CTS3 monitor so that I could see what trouble codes came up and reset this one. I have reset this code usually once a day. This has been going on for 3 months and it has been to dealer 3 times already. I work out of my truck so it is very inconvenient to just leave and drive one of the loaner cars. My dealer has been great, they did the recall on the engine coolant heater and have tried to correct this problem with no luck. Does anyone on here have any clue what this is? Thanks
 

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2018 GMC 2500Hd Denali L5P Duramax
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See if your fuel tank is collapsed from a clogged vent line. Mine is currently in the shop for the same code. I cleaned the MAP sensor like I had seen on other forums and then cleared the code. It was back 2 days later so I sent it to the dealership....3 weeks ago waiting on a fuel tank now.
 

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See if your fuel tank is collapsed from a clogged vent line. Mine is currently in the shop for the same code. I cleaned the MAP sensor like I had seen on other forums and then cleared the code. It was back 2 days later so I sent it to the dealership....3 weeks ago waiting on a fuel tank now.
Haven't been under there yet but did this, cleaned sensor and loosened fuel cap. have traveled 750 miles with no codes.
 

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These trucks do not have a vent valve. The tank vents back into the filler tube. You can see the inlet for the vent tube if you look down the filler tube, it is an inch or two down the tube. Or look at the parts diagram on a GM parts site to see the setup.

My truck had P026D and Chevy was clueless. They changed both NOX sensors and the the MAF sensor, cleaned the MAP sensor. Finally did a fuel filter change, fuel filter housing clean and flushed the fuel line with 2-3 gallons of fuel.

Ultimately, I talked to the guys at PBP Motorsports. They thought since my total mileage/engine hours was so low when I just bought the truck, ~11mph (33,000miles/3,000hours) that my exhaust system was gunked up from too much idleing and poor regen cycles. Lately I have been taking my truck on the highway for every regen cycle. After about 5 highway regens, the P026D has gone away completely. Over a month and about 1,000 miles, no P026D pending, no P026d in the history, no CEL. (LOL prolly come back tomorrow).

I've heard a lot of stories about P026D, so maybe it is a fickle code with many causes/solutions. But in my case I think the gunked up exhaust was the problem. Check your miles/engine hours. Chevy has a bulletin that basically says 33mph is the optimal value. If yours is below that, you probably have a gunked up exhaust and need to do several highway regens. Good luck
 

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These trucks do not have a vent valve. The tank vents back into the filler tube. You can see the inlet for the vent tube if you look down the filler tube, it is an inch or two down the tube. Or look at the parts diagram on a GM parts site to see the setup.

My truck had P026D and Chevy was clueless. They changed both NOX sensors and the the MAF sensor, cleaned the MAP sensor. Finally did a fuel filter change, fuel filter housing clean and flushed the fuel line with 2-3 gallons of fuel.

Ultimately, I talked to the guys at PBP Motorsports. They thought since my total mileage/engine hours was so low when I just bought the truck, ~11mph (33,000miles/3,000hours) that my exhaust system was gunked up from too much idleing and poor regen cycles. Lately I have been taking my truck on the highway for every regen cycle. After about 5 highway regens, the P026D has gone away completely. Over a month and about 1,000 miles, no P026D pending, no P026d in the history, no CEL. (LOL prolly come back tomorrow).

I've heard a lot of stories about P026D, so maybe it is a fickle code with many causes/solutions. But in my case I think the gunked up exhaust was the problem. Check your miles/engine hours. Chevy has a bulletin that basically says 33mph is the optimal value. If yours is below that, you probably have a gunked up exhaust and need to do several highway regens. Good luck
I have been dealing with that code for about 3 months now. It originally happened at a rest area going about 5 miles an hour, went and got it reset.. I got home, cleaned the MAF that was plugged up to shit (all other maintenance has been done--fuel filter, trans filter, oil, etc)

It came back on in a parking lot after about 500 miles, got it reset and it lasted about 30 miles.

I finally took it in to my diesel guy and he said that my air filter was clogged (never even checked that), so he swapped it out, reset my parameters in his tool and it stayed off for almost 800 miles, then boom...back on. He told me if it came back on that he would replace the Nox sensors next, but since I was under warranty (52k miles) to take it to a dealer because it would be covered.

I took it to the dealership and they said one of the injectors was failing or has failed---they replaced all 8. I spoke with a couple guys there who have been there for 30+ years and apparently the 2017 and early 2018's had shitty injectors----they are now on the 3rd and final revision of the the original injectors---so the issue is supposed to be resolved (must have computer updated after injectors are replace). I then went to a few FB groups and they were saying the same thing--if the MAF is extremely gunked up, most likely it's the injectors causing the issue. The MAF does get dirty, but not like mine was (completely black and caked on).

Only on about 300 miles and no code listed or pending, or permanent. We will see.
 

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21 Silverado 2500HD Crew Cab Standard Box 4x4 Z71 with Duramax and Allison 10 speed
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Bought yesterday, noticed the CEL was on the dash so asked them about it - truck has 23 miles on it and Boom I went home without my brand new 21 model for this stupid P026D error. They pulled the DEF Tank and injection pump and switched it out and are delivering the truck in a few hours. But as you can tell I'm on researching to see how common this is and if it's going to happen again soon. What are ya'lls thoughts, I asked for warranty extended due to this but have never went home without a new vehicle purchase due to a damn part issue....
 

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Well after many months, the P026D is back. I wonder if the 18-NA-361 (Fuel Filter/system flush) was the trick. I say that because my filter is now down to 60% life remaining.

But, on the other hand, I found this new bulletin related to that code (20-NA-197) that says the fuel pressure sensor wiring connector gets corroded and needs to be cleaned/replaced. This makes sense to me. My truck always estimates the wrong MPG on the DIC. For example, DIC always says 17.2 mpg, but direct measurement is 14.5-16.5 depending on the number of regens between fillups. 1 regen = 16.5 mpg, 2 regens = 15.5 mpg, 3 regens = 14.5 mpg. Checking the status of the connector is something I could do but I cannot find it. I found a connector on the drivers side at the top back of the engine that looks like it goes to the fuel rail, but it only has two wires, not 4 like the one pictured in the bulletin. I tried to find it in an online in a parts diagram, but have not figured it out yet.

Can anyone help me locate the fuel pressure sensor wire connector on a 2017 L5P?

Thanks-




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Well after many months, the P026D is back. I wonder if the 18-NA-361 (Fuel Filter/system flush) was the trick. I say that because my filter is now down to 60% life remaining.

But, on the other hand, I found this new bulletin related to that code (20-NA-197) that says the fuel pressure sensor wiring connector gets corroded and needs to be cleaned/replaced. This makes sense to me. My truck always estimates the wrong MPG on the DIC. For example, DIC always says 17.2 mpg, but direct measurement is 14.5-16.5 depending on the number of regens between fillups. 1 regen = 16.5 mpg, 2 regens = 15.5 mpg, 3 regens = 14.5 mpg. Checking the status of the connector is something I could do but I cannot find it. I found a connector on the drivers side at the top back of the engine that looks like it goes to the fuel rail, but it only has two wires, not 4 like the one pictured in the bulletin. I tried to find it in an online in a parts diagram, but have not figured it out yet.

Can anyone help me locate the fuel pressure sensor wire connector on a 2017 L5P?

Thanks-




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Interesting read, CEL came back with the p026 and my scanner says high fuel flow quantity. Also noted was my rail psi on the scanner, it was in red numbers, not blue. Engine runs fine, no smoke or extended cranks.

I'll look for the switch and see if it needs to be cleaned.

Thx
 

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Well after many months, the P026D is back. I wonder if the 18-NA-361 (Fuel Filter/system flush) was the trick. I say that because my filter is now down to 60% life remaining.

But, on the other hand, I found this new bulletin related to that code (20-NA-197) that says the fuel pressure sensor wiring connector gets corroded and needs to be cleaned/replaced. This makes sense to me. My truck always estimates the wrong MPG on the DIC. For example, DIC always says 17.2 mpg, but direct measurement is 14.5-16.5 depending on the number of regens between fillups. 1 regen = 16.5 mpg, 2 regens = 15.5 mpg, 3 regens = 14.5 mpg. Checking the status of the connector is something I could do but I cannot find it. I found a connector on the drivers side at the top back of the engine that looks like it goes to the fuel rail, but it only has two wires, not 4 like the one pictured in the bulletin. I tried to find it in an online in a parts diagram, but have not figured it out yet.

Can anyone help me locate the fuel pressure sensor wire connector on a 2017 L5P?

Thanks-




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Found it dude, right side head front beside alternator. Looks like a real PITA.

Gm-techlink.com/?p=14070

Going digging tomorrow!
 

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Yeah i couldn't get mine off. I could get the clip unhooked but no leverage to pull it off. I figure I'll check it when I replace the intercooler pipes.
 

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Help me out here, my truck has dual alternators one on each side, but you are saying it is behind the alternator on the passenger side of the vehicle? I know that is that the diagram seems to show and that is where I looked, but I could not see anything.
 

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Found it dude, right side head front beside alternator. Looks like a real PITA.

Gm-techlink.com/?p=14070

Going digging tomorrow!
Pita it is, went out and looked for it. Air intake hose and maybe charge air cooler hose have to go, maybe some mounting brackets.

You can see it, look at about 11 o'clock left of alternator between fresh air inlet and EGR on the right head. I'm not going to be real.quick about cutting wires and replacing connector just yet. See how bad first.

Update later...
Help me out here, my truck has dual alternators one on each side, but you are saying it is behind the alternator on the passenger side of the vehicle? I know that is that the diagram seems to show and that is where I looked, but I could not see anything.
Yes, my 18 is, look left of passenger alternator between cooler and fresh air piping. Horizontal 4 wire connector just like diagram. Its going to be a beach. Id say air cleaner and cooler piping has to go.
 

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I was looking all over in there with a flash light, even took the intake hose off, I must have missed it. But I'll take your word for it about being a PIA.

CRC has a spray cleaner just for electrical connectors. I used it before on the main airbag plug in my 98 Dodge and it worked fine.

Thanks!
 

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I was looking all over in there with a flash light, even took the intake hose off, I must have missed it. But I'll take your word for it about being a PIA.

CRC has a spray cleaner just for electrical connectors. I used it before on the main airbag plug in my 98 Dodge and it worked fine.

Thanks!
It's basically tucked right behind the intercooler pipe.
 

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Remember that RIGHT and LEFT are relative. To some Right is the driver's side, to others, it is the passenger side. The standard meaning as used by GM for our trucks is left = drivers side. Now you have to figure out where that connector really is.
 

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I've cleared my P026D code several times, and it comes back on at each and every start up. Do you guys think this is covered under the factory warranty? I bought mine used with no warranty, and it has about 66k miles on it now.
 
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