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AutoCodes – GMC – P0171 2016 GMC Sierra

P0171 2016 GMC Sierra Code - Fuel Trim System Lean Bank 1

Quick Answer

The Engine Control Module (ECM) controls a Closed Loop air/fuel metering system to provide the best possible combination of drivability, fuel economy, and emission control. Common causes include Dirty or Restricted Air Filter, Dirty or Faulty Mass Air Flow (MAF) Sensor, Intake Air Leaks. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0171 2016 GMC Sierra indicates Fuel Trim System Lean Bank 1.
Common causes
Common causes include Dirty or Restricted Air Filter, Dirty or Faulty Mass Air Flow (MAF) Sensor, Intake Air Leaks.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
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Code Popularity 396
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Jul 23, 2023
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Code P0171 2016 GMC Sierra Description

The Engine Control Module (ECM) controls a Closed Loop air/fuel metering system to provide the best possible combination of drivability, fuel economy, and emission control. The ECM monitors the Heated Oxygen Sensor (HO2S) signal voltage and adjusts the fuel delivery based on the signal voltage while in Closed Loop. A change made to the fuel delivery changes the long and short-term fuel trim values. The short-term fuel trim values change rapidly in response to the HO2S signal voltages. These changes fine-tune the engine fueling. The long-term fuel trim values change in response to trends in the short-term fuel trim. The long-term fuel trim makes coarse adjustments to fueling to re-center and restore control to short-term fuel trim. The ideal fuel trim values are around 0 %. A positive fuel trim value indicates that the ECM is adding fuel to compensate for a lean condition. A negative fuel trim value indicates that the ECM is reducing the amount of fuel to compensate for a rich condition. The Diagnostic Trouble Code (DTC) will be set when the average long-term fuel trim weighted average value is greater or less than a calibrated value.
OBDII Code P0171 2016 GMC Sierra - Fuel Trim System Lean Bank 1 - AutoCodes.com
P0171 2016 GMC Sierra Code - Fuel Trim System Lean Bank 1
What does this mean?

What are the Possible Causes of the DTC P0171 2016 GMC Sierra?

  • Dirty or Restricted Air Filter
  • Dirty or Faulty Mass Air Flow (MAF) Sensor
  • Intake Air Leaks
  • Exhaust Gas Leaks
  • Fuel Contamination
  • Faulty or Clogged Fuel Injectors
  • Faulty Front Heated Oxygen Sensor
  • Ignition Misfiring
  • Low Fuel Pressure
  • Positive Crankcase Ventilation (PCV) Hose Leaks
  • Engine Control Temperature (ECT) inaccurate readings

How to Fix the DTC P0171 2016 GMC Sierra?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

The P0171 code means that more air than gasoline is detected in the exhaust gases exiting the combustion chamber. If the P0171 is set in along with the P0174 code, it is highly 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 Mass Air Flow (MAF) Sensor. If the problem persists the MAF or Front Heated Oxygen (O2) Sensor will need to be replaced.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0171 2016 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0171 2016 GMC Sierra code?

Need more information on how to fix the P0171 2016 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0171 2016 GMC Sierra Code

1. What are the common symptoms of OBDII code P0171 on a 2016 GMC Sierra?

- Common symptoms include rough idling, reduced engine performance, and an illuminated check engine light.

2. What does the OBDII code P0171 Fuel Trim System Lean Bank 1 indicate in a 2016 GMC Sierra?

- This code indicates that the engine is running too lean, meaning there is too much air and not enough fuel in the air-fuel mixture.

3. What are the possible causes of OBDII code P0171 on a 2016 GMC Sierra?

- Common causes include a vacuum leak, faulty oxygen sensor, dirty or clogged fuel injectors, or a malfunctioning mass airflow sensor.

4. How can I diagnose the OBDII code P0171 on my 2016 GMC Sierra?

- Diagnose by checking for vacuum leaks, inspecting the oxygen sensor, testing the fuel injectors, and cleaning or replacing the mass airflow sensor.

5. What are some tips for repairing OBDII code P0171 on a 2016 GMC Sierra?

- Repair tips include fixing any vacuum leaks, replacing the oxygen sensor if faulty, cleaning or replacing clogged fuel injectors, and cleaning or replacing the mass airflow sensor.

6. Can a dirty air filter trigger the OBDII code P0171 on a 2016 GMC Sierra?

- Yes, a dirty air filter can restrict airflow, leading to a lean air-fuel mixture, which may trigger the P0171 code.

7. Is it safe to continue driving my 2016 GMC Sierra with the OBDII code P0171?

- It is not recommended to drive with the P0171 code as it can cause damage to the engine over time and may result in decreased fuel efficiency.

8. How much does it typically cost to repair the OBDII code P0171 on a 2016 GMC Sierra?

- The cost of repairs for the P0171 code can vary depending on the underlying issue but may range from $100 to $500 or more.

9. Can a faulty fuel pump cause the OBDII code P0171 on a 2016 GMC Sierra?

- Yes, a failing fuel pump can lead to inadequate fuel delivery, causing a lean air-fuel mixture and triggering the P0171 code.

10. Will resetting the OBDII code P0171 on my 2016 GMC Sierra make it go away permanently?

- Resetting the code may temporarily turn off the check engine light, but if the underlying issue is not addressed, the code is likely to reappear.

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