Crazy Coding 2003 GMC Yukon 5.3L non-flex

Asked by May 20, 2017 at 06:30 AM about the 2003 GMC Yukon SLT 4WD

Question type: Maintenance & Repair

Back in November I brought my 2003 Yukon SLT 5.3L non flex fuel for inspection. It passed the safety but it had a code. Knock sensors both 1 and 2. I replaced the two sensors and the code went away. After that it coded P0101 my MAF sensor, replaced 5 times and finally got rid of that code. During the MAF issues I was also getting the running rich bank 1 and 2. Replaced the MAP sensor and the rich code went away but started getting the Knock sensor 1 and 2 code back again and now the rich bank 1 and 2. I've driven over 6000 miles. the intake is OK no leaks. I replaced the Exhaust manifolds and gaskets. new spark plug wires 8MM new coils MDS high output coils and new plugs. replaced the electrical plug on the MAF. Could it be the ECU ?
I had the fuel rail pressure checked and they said it was OK.
I took it out after clearing codes drove it about 45 miles and now I got a code for 1 O2 sensor not operating. The thing that gets me is the truck is running great has lots of power and the mileage is good, idles fine. The codes just seem to be coming up at random, sometimes it's just knock sensor bank 1. another time it codes both knock sensors. another time I'll get no knock senor but both banks running rich. fortunately the MAF has not returned. Note: I did have the truck running on hydrogen about 3 years ago and had a controller that was sending false info to ECU, like instead of water temp at 196, I would send 205, changed the Map info, the 02 sensors was sending false info to ecu . could all that have caused problems in the ecu?

1 Answer

Forgot to mention truck has 138K miles.

Your Answer

GMC Yukon Experts

  • #1
    clayduster71
    Reputation
    2,710
  • #2
    David Boccabello
    Reputation
    870
  • #3
    Drpsychmom
    Reputation
    690
View All

Related Models For Sale

Used Chevrolet Tahoe
4 Great Deals out of 721 listings starting at $4,995
Used Cadillac Escalade
4 Great Deals out of 436 listings starting at $4,000
Used GMC Yukon XL
10 Great Deals out of 575 listings starting at $2,800
Used Chevrolet Suburban
8 Great Deals out of 388 listings starting at $5,871
Used GMC Sierra 1500
266 Great Deals out of 10,821 listings starting at $2,995
Used Ford Expedition
12 Great Deals out of 338 listings starting at $2,900
Used Chevrolet Silverado 1500
179 Great Deals out of 11,110 listings starting at $999
Used Ford F-150
472 Great Deals out of 10,109 listings starting at $3,450
Used Jeep Grand Cherokee
103 Great Deals out of 2,759 listings starting at $1,695
Used Ford Explorer
50 Great Deals out of 1,454 listings starting at $2,800
Used Dodge Durango
81 Great Deals out of 1,058 listings starting at $2,998
Used Toyota 4Runner
6 Great Deals out of 471 listings starting at $5,990
Used Toyota Sequoia
9 Great Deals out of 94 listings starting at $4,500
Used Cadillac Escalade ESV
161 listings starting at $4,495

Used Cars For Sale

2018 GMC Yukon SLT 4WD For Sale
13 listings starting at $72,205
2017 GMC Yukon SLT 4WD For Sale
154 listings starting at $59,967
2016 GMC Yukon SLT 4WD For Sale
14 listings starting at $54,768
2015 GMC Yukon SLT 4WD For Sale
12 listings starting at $47,894
2014 GMC Yukon SLT 4WD For Sale
6 listings starting at $37,750

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.