Chevy Silverado 2020 5.3 with 34,000 miles throwing P0171 & P0174 codes just showed up. BONE stock. Only thing to report is that I just had a one day trip with 300 or so miles and filled it up with gas just before I got home . I didn't notice if it came on yesterday but noticed it today. Otherwise all normal. Any usual problems with this years 5.3 ? Visually ,all looks good
P0171 -P0174 2020 Silverado 5.3
- Thread starter tcurlee
- Start date
Running lean on both banks. I would start by confirming the connections between the mass airflow sensor and the throttle body; give them a shake make sure the hose clamps are firmly attached. Make sure the PCV hose(s) are connected.
Are you able to get LT & ST fuel trim data? If so, how do bank 1 and bank 2 compare?
Are you able to get LT & ST fuel trim data? If so, how do bank 1 and bank 2 compare?
Mooseman
Moderator
Everything looks tight and buttoned up as far as connections go. I had the truck out today and noticed the Check Engine light was out. I hooked up the scanner and its showing the codes pending ( P0171 & P0174 ). Also my gas mileage seems to be down as well but that might be due to I just filled up and have only put about 30 miles on it since I reset. I'm getting ready to go out of state early tomorrow for a week ( using another veh. ) so when I get back I'll check those fuel trim numbers and report back. Thanks for your replies !! 
There is a TSB covering these PXXX Codes due to a problem with **** Lean EFIs linked and attached below:
en.wikipedia.org
**** Evidently, GM was having trouble at The Factory getting some of these Vehicles to Pass their OEM Emissions Tests and their solution was to "Mix-N-Match" Some Lean and FAT performing EFIs based upon their batch Outputs in order to get them to Pass the EPA Muster. Clever...Or Clumsy?
Read Deeply into the 'Fine Print' of the TSB for this implication.
Chevrolet Silverado - Wikipedia
**** Evidently, GM was having trouble at The Factory getting some of these Vehicles to Pass their OEM Emissions Tests and their solution was to "Mix-N-Match" Some Lean and FAT performing EFIs based upon their batch Outputs in order to get them to Pass the EPA Muster. Clever...Or Clumsy?
Read Deeply into the 'Fine Print' of the TSB for this implication.
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Might be wise to start with the dealer. Being its a 2020, it might fall under the emissions warranty.
Getting conflicting answers as to what the warranty is thou.. I see 5/60 and 2/24.
Getting conflicting answers as to what the warranty is thou.. I see 5/60 and 2/24.
Sorry, I really should've gotten back to this thread earlier for an update. As it turns out, it seems to be a type of fuel problem. I filled up at a local Royal Farms station using their 88oct. E-15 (not E-85 ) and that's when the problem with the codes started. I didn't put the two together initially. I got it down to about 1/2 tank and put a fuel system cleaner that deals with ethenol too and ran that down to about a 1/4 tank then filled up with Shell 93, cleared the codes and went on my merry way. No codes since then and gas mileage went back to normal. Maybe our trucks are sensitive to fuel types ? It seemed to be my problem anyway. Anyone else have this issue ?
-- 2020 Silverado 5.3 stock
-- 2020 Silverado 5.3 stock
