P0101 MAF 2004 5.3

ChevroletTough · August 27, 2020

Hey guys, my CEL has come on twice now and cleared. Checked it finally. P0101 MAF sensor issue. I have a bad feeling I have a cat or both plugging.

Going to replace my factory MAF sensor as its aged now on my 2004. I just have this awful feeling the p0101 is a false code for a cat or both going bad. Sure hope I'm wrong. If not, I'll be looking at all new oxygen sensors and a new y pipe with cats. I don't think I'll do the cat delete as the truck will smell like my catless 1 ton.

I know there are threads on this, but wanted to start my own. New MAF arrived today, I'll swap it out. I did consider cleaning my stock one since I have cleaner but just opted to get a new one since they really aren't that expensive anymore.

ChevroletTough · August 27, 2020

So I do run a K&N and might be that the MAF is also dirty from it. Either way I'll check it first. Hoping its not a cat or intake leak.

CamGTP · August 27, 2020

If the exhaust was plugged, you'd have zero power and the cats would be glowing red because it can't get the exhaust out. Seeing that at night would be easy.

Or hook a back pressure gauge up into the front o2 sensor port before spending hundreds of dollars on exhaust parts. A free flowing exhaust will have ~1 psi of back pressure.

ChevroletTough · August 28, 2020

Can’t be my cats then.

Pulled MAF, enough dust fell out to make me think it was dirty. Had a light right next to it. Cleaned it and still swapped it. Pretty sure I’m done with K&N for good. Betting this was my issue.

Will test tomorrow.

I forgot: intake was done when knock sensors were replaced.

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ChevroletTough · August 31, 2020

Pulled without issues. Cleared the stored code after we got home.

Pulling again next weekend so I’ll get to test again. The cel didn’t come on.

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ChevroletTough · September 7, 2020

Pulled again this weekend. No service lights or issues. Should be good to go!

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dukbludvl · November 28, 2020

I just bought a used 2003 Yukon 2wd 5.3L with 150k miles on it about a month ago from the only other owner who got it new in 2003 and had it for 17 years. This is my third Yukon from the 2000-2006 body style -- first was a brand new 2000 that I put nearly 400k miles on, second was a 2005 that I bought with 190k miles and I put 100k more on it before the trans went and I decided not to fix it.

Anyway, previous owner installed a K&N cold air intake years ago, and the K&N filter is quite dirty. I've had some rough idle issues, and the other day it stalled out 3 or 4 times while engine was warm and I was going from Park to Reverse trying to back out of a spot. I'm guessing the throttle body is also probably dirty/sticking. My old 2000 Yukon did that for the first time in 2002 and it freaked me out. That 2000 Yukon had drive by cable, so I just moved the butterfly plate in the TB and cleaned all around it good and it was good fro the next 100k miles or more. This 2003 is drive by wire, so I think I need to find a buddy to get on the accelerator pedal to open up the butterfly plate while I clean around it -- is that right? Anyway, I don't like the idea of the cold air intake. So, my plan is also to reinstall the stock air filter box and get rid of the cold air intake. I'll clean up the TB when I do that hopefully this weekend.

Now, for a perhaps related issue -- or maybe it's a totally separate issue. I had a CEL code on last week before I replaced the plugs/wires with new Delcos, and I had it read and it came back as P0420, Catalyst System Efficiency Below Threshold (Bank 1). The CEL stayed on for a day, then went off for a day -- did that most of last week. Now, after the plugs/wires change, the CEL has been on steady, so I just had it read again at AutoZone tonight. It's showing the following:

P0420 Catalyst System Efficiency Below Threshold (Bank 1)

P0101 Mass or Volume Air Flow Circuit Range/Performance

P0102 Mass or Volume Air Flow Circuit Low Input

P0101 Mass or Volume Air Flow Circuit Range/Performance

Not sure why the same P0101 code is on there twice. Anyway, the AutoZone print out say "ASE certified Master Technicians have seen this issue on your type of vehicle and the most like solution is: Repair Engine Control Module (ECM) Wiring.

Anybody have any insights into what might be going on with this? Do you think I have an air quality issue that might be fixed by going back to the stock air box and intake? I've also got a fairly new MAF sensor I can pull off that old 2005 Yukon (the one with the bad trans) and put in here, so I might do that just to see if it clears up these codes. Please help if you have any ideas about what's going on with this. Thanks!