This issue is notorious for all L5P Duramax models from 2017 to 2019, as well as 2020 and newer Duramax trucks. As you can see, we’ve got the “Service Emission System” message right here along with the check engine light. I’m going to run the code and let you guys know exactly what it is.
The truck is going to idle slightly rough, and most of the time you won’t be able to go over 50 to 60 mph. Your symptoms may vary slightly, but for the most part, they are all going to be similar. You’ll hear it loping a little bit, and it idles kind of rough—it doesn’t idle as smoothly as it should. Yep, right there. I don’t know if you guys heard it on the camera.
L5P Duramax injector pigtail—here is the part number if you need it:And this is what it looks like. In this particular truck, it is injector pigtail number five, meaning it’s on the passenger side because it goes 1, 3, 5, and 7 on that side. So, we have to remove this heat shield right here. I think it’s 1, 2, 3, 4, 5, 10mm bolts that I see. I’ll keep you guys updated if there are more.
Alright, you just remove one, two, three, four bolts from this heat shield. It’ll just come right out. We’ll move it out of the way and put it right here. Now, it gives us a little bit more access. I think we can remove this one as well—this one right here.
Undo the red clip and then, sometimes, these are a pretty big pain in the butt to do, but press down on this tab right here and hopefully, it slides out. There you go. Oh man, I was actually fighting this for a lot longer than I was recording because the tab only slid out halfway. So, y’all really make sure to get a flathead screwdriver and push this all the way out. Now, we’re going to cut it somewhere right here and splice our new injector pigtail.
This is a new injector pigtail, AC Delco OEM from the dealership. It comes with these connectors. I am personally not going to be using this—I prefer to use the heat shrink ones, so I’ll show you guys how it’s done.
Electrical tape—good as new. Actually, I’m going to redo this.Alrighty, change of plans. I had to redo this, so I had to cut the wires a little bit shorter because the first time, the wire was a little too long. So, where it bent right here, it was the connecting point, and I didn’t want that. Now it’s shorter, so where it bends right here—I’ll show you guys—once you plug this in, it bends right there, which is better than bending right where the connection is.
All we got to do next is put some tape around it. I also decided to use the supplied heat shrink SL connector because, with the crimp connector, I feel like I could get a better and more solid connection over the heat shrink one with the solder in the middle. Also, I don’t think this heat gun was strong enough to melt the solder, and I did not want to put a lighter or a torch in there to melt the solder in the connection, like this one right here. So, I used the supplied one. I think it should work pretty well. Let’s go ahead and tape this up, connect it back to the injector, and see if we have any issues.
Alrighty, just like that, the new pigtail has been installed. I’m still not 100% a fan of how it bends right there, but oh well, hopefully it lasts. Otherwise, I’d have to cut it all the way to here and redo it. But I think this should fix the issue.
Alrighty, no “Service Emission System” messages popping up, no check engine light, and the truck idle is great. I’m going to roll the windows down and up. But yeah, the truck idle is good. So there you have it—injector pigtail replacement on an L5P Duramax.
This version retains all the original details while improving readability and flow.
