Engine-Codes - Hummer - P0171 Hummer

P0171 Hummer Code - Fuel Trim System Lean Bank 1

- Code Popularity: 45,385 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC P0171 Hummer?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Intake air leaks
  • 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

Code Tech Notes

If the P0171 is combined with the P0174 code, it's very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replace the air filter and clean the air flow meter. If the problem persists the front oxygen (O2) sensor may need to be replaced.
The P0171 code could also be caused may be caused by one or more of the following: debris on the 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 HUMMER models:
2003-2008 HUMMER H2
2006-2008 HUMMER H3
2003-2008 HUMMER Factory Service Bulletin OBDII Code P0171

⚠ Does your Hummer have Safety Recalls? → Check here

How to Fix the DTC P0171 Hummer?

Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

Search for P0171 Hummer Questions and Answers: Search here →

What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P0171 Hummer code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

When is the Code Detected?

- Fuel injection system does not operate properly.
- The amount of mixture ratio compensation is too small. (The mixture ratio is too lean.)

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Excessive Fuel Consumption

What Does the P0171 Hummer Code Mean?

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.

P0171 Hummer Code - Fuel Trim System Lean Bank 1

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