I have a 2006 Denali with the 6.0 LQ9. Roughly 245k on the clock, but it has been maintained and taken care of very very well. These two codes have persisted, but the truck doesn't respond like its running lean. throttle response is normal, power is normal, idle is normal, fuel mileage doesn't seem to be effected. There's also many new parts on it such as the fuel pump, O2 sensors, Throttle body and more. I had this issue on my camry (given it was a four cylinder so only one bank) and it seemed to be a unique reason for the code. I wanted to ask if anyone has had this issue and what their fix was before i dive into this.
P0174 and P0171 Both Sides Running Lean
- Thread starter Gstepha0
- Start date
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strutaeng
Full Access Member
Check for fuel pressure. Fuel delivery problems usually affects BOTH banks, within a certain % of each other. Check at idle and while driving.
Often, the ECU can still command fuel adjustment (up to like +/- 25%) you won't notice driveability issues.
Don't assume something if fine because it's new or has already been replaced.
Check for vacuum leaks as well.
Often, the ECU can still command fuel adjustment (up to like +/- 25%) you won't notice driveability issues.
Don't assume something if fine because it's new or has already been replaced.
Check for vacuum leaks as well.
Ditto on the vacuum leak check as @strutaeng noted, or a leak in the intake between the MAF and the throttle body.
Check both the long- and short-term fuel trims to see if they're out of whack. If it's adding too much fuel it could kill your cats over time.
Check both the long- and short-term fuel trims to see if they're out of whack. If it's adding too much fuel it could kill your cats over time.
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