Hi Guys, I have a 2003 Yukon SLT 4 wheel drive with 174,000 miles. Truck runs good and good mileage. For over 4 years it has coding issues and keeps it from passing the yearly inspection. Over the last 4 years I replaced the Mass Air sensor, knock sensors, Map sensor, wires, fuel injectors, manifold gasket and the usual air filter, plugs. The trans was completely rebuilt at 167,000 2 years ago. I use this truck very little. Before I had the trans done I had gone in for inspection and it failed. Code ( running rich) I made some corrections and went back and he said he could still see that there was a code that I had cleared. He told me to drive it 100 miles and if it didn't come back on bring it in. Long story shorter after 5000 miles the light was off long enough to get the inspection. He said it passed but the light will come back on ?? It did and I've been going thru this for a few years now. I took it to a tuner to see if he could figure it out, he looked at the O2 sensors while running and other sensors and he couldn't find anything that would cause the codes. He even felt bad and only charged me $25. Now it's coding running lean which it isn't I continue to check for air leaks but nothing. Has anyone had this issue ? it's in good shape and runs good but evading the cops is something I'm getting tired of.
2003 Yukon SLT 4 Wheel Drive Code Issues
- Thread starter zmann96
- Start date
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George B
¯\_(ツ)_/¯
What are the code numbers?
I can't remember I've cleared them on my scanner it gave the code then either rich or lean depending on code, then one a while back was the code and it said knock sensor I replaced them both, code came back a few times but then it went away. I have a good knowledge of cars and engines but when this stumps an engine tuner with much better equipment than mine that's making me wonder. I even replaced with a 30 day return on a ECU, that didn't change a thing.
sonic_the_hedgeh
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I just had the knock sensors replaced in mine. While they were at it I had the seals replaced for the intake. I even had a misfire code, running lean, and knock sensors.
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sonic_the_hedgeh
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Basically the lean error codes on mine were the head gasket leaking. So bought a kit with all the head seals and my error codes are gone. Hope this helps
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Take a pic with your phone every time a code is read so you have a record. They are used for diagnosis and that then you can go back and see what codes came up on what day. It’s hard to help you without those.
If you look at short- and long-term fuel trims at idle and a higher RPM you'll be able to see if it's running lean or rich, and can go from there. As @Rocket Man said, documenting the codes is very helpful.
HiHoeSilver
Away!
Could be bank 1 or 2 or both. You need the actual code to do any good here. Also when you read the code you can see the freeze frame data set. Any time a vehicle sets a trouble code, it saves the data from that instant, as well.
The next thing would be looking at fuel trims like @Fless said. It would help to see live data so you can see what happens at idle, under load, etc.
Lean codes could also be a weak fuel pump or a vacuum leak. The live data can tell you which spot to look.
The guy knew your light would be back because he saw a pending code, which happens before a stored code triggers the CEL.
The next thing would be looking at fuel trims like @Fless said. It would help to see live data so you can see what happens at idle, under load, etc.
Lean codes could also be a weak fuel pump or a vacuum leak. The live data can tell you which spot to look.
The guy knew your light would be back because he saw a pending code, which happens before a stored code triggers the CEL.
