P0171 GMC - Fuel Trim System Lean Bank 1
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection
The P0171 code could also be caused may be caused by one or more of the following: debris on MAF sensor causing an incorrect reading, improper oil level, low or high fuel pressure or Engine Control Temperature (ECT) Sensor reading inaccurate.
There is a factory service bulletin for the following GMC models:
2000-2008 GMC Sonoma
2000-2008 GMC Sierra
2000-2008 GMC Yukon
2000-2008 GMC Yukon XL
2001-2008 GMC Denali
2001-2008 GMC Denali XL
2001-2008 GMC Savana
2002-2008 GMC Envoy
2002-2008 GMC Safari
2002-2008 GMC Jimmy
2000-2008 GMC Factory Service Bulletin OBDII Code P0171
2006 Trailblazer P0171
User Submitted Video
- The amount of mixture ratio compensation is too small. (The mixture ratio is too lean.)
- Excessive Fuel Consumption
The Engine Control Module (ECM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. Fuel delivery is controlled differently during Open Loop and Closed Loop. During Open Loop, the ECM determines fuel delivery based on sensor signals without heated oxygen sensor (HO2S) input. During Closed Loop, the ECM adds HO2S inputs to calculate the short and long term fuel trim (FT) adjustments. If the HO2S indicates a lean condition, the fuel trim values will be above 0 percent. If the HO2S indicates a rich condition, the FT values will be below 0 percent. The short term FT values change rapidly in response to the HO2S voltage signals. The long term FT makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1.
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Any information is appreciated. Thanks