P0171 system too lean bank 1

dlnelsonroca

Original poster
Member
Dec 3, 2014
36
Cacalote, Oaxaca, Mexico
Hello! My Trailblazer has given me the code P0171 off and on for a few months now. The odd symptom that I'm hoping you can help me diagnose is that it comes on for a few days, then goes off for a day or half a day, and then on again, repeatedly. I've looked for a vacuum leak without success. What do you think? Thanks!
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Check the intake manifold bolts. Next, the SAIS is a usual suspect for lean issues.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Secondary Air Injection System. Search for it here and you find lots of info.
 

dlnelsonroca

Original poster
Member
Dec 3, 2014
36
Cacalote, Oaxaca, Mexico
Thanks all! I'm going to check the intake manifold bolts as soon as I can. Hopefully that will take care of it. If not then I'll look at the Secondary Air Injection System. Yes, there's quite a bit of info about that here! My Trailbalzer is a 2004 LS extended version with 4x4, the inline six cylinder engine, and with about 140,000 miles on it now. I have a scanner, an Autolink AL539. I'm not sure if it reads live data or not, never having used that, and not really being a mechanic. I'm just too far from good mechanics to not try to do most work myself!

I just checked the scanner manual, and it does appear to do live data.
 

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