AutoCodes – GMC – P0171 2015 GMC Sierra

P0171 2015 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 2015 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 363

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 23, 2023

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0171 2015 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 2015 GMC Sierra - Fuel Trim System Lean Bank 1 - AutoCodes.com — P0171 2015 GMC Sierra Code - Fuel Trim System Lean Bank 1

What does this mean?

What are the Possible Causes of the DTC P0171 2015 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 2015 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 2015 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.

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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 2015 GMC Sierra Code

1. What does OBDII code P0171 for a 2015 GMC Sierra mean?

The code P0171 on a 2015 GMC Sierra indicates a lean fuel mixture condition in Bank 1 of the engine, specifically related to the Fuel Trim System.

2. What are the common symptoms of OBDII code P0171 on a 2015 GMC Sierra?

Common symptoms of code P0171 on a 2015 GMC Sierra may include rough idling, poor acceleration, decreased fuel efficiency, and potential engine misfires.

3. What are the possible causes of OBDII code P0171 on a 2015 GMC Sierra?

Common causes of code P0171 on a 2015 GMC Sierra include a vacuum leak, faulty oxygen sensor, clogged fuel filter, malfunctioning mass airflow sensor, or issues with the fuel injectors.

4. How can I diagnose OBDII code P0171 on my 2015 GMC Sierra?

To diagnose code P0171 on a 2015 GMC Sierra, you can start by checking for vacuum leaks, inspecting the oxygen sensor, testing the mass airflow sensor, examining the fuel filter, and ensuring proper fuel pressure.

5. Can a dirty air filter trigger OBDII code P0171 on a 2015 GMC Sierra?

Yes, a dirty air filter can restrict airflow to the engine, leading to a lean fuel mixture and triggering code P0171 on a 2015 GMC Sierra.

6. Will driving with OBDII code P0171 on a 2015 GMC Sierra cause further damage?

Continuously driving with code P0171 on a 2015 GMC Sierra can potentially cause damage to the catalytic converter and other engine components over time due to the lean fuel condition.

7. How can I fix OBDII code P0171 on my 2015 GMC Sierra?

Repairing code P0171 on a 2015 GMC Sierra typically involves fixing the root cause, such as replacing a faulty oxygen sensor, fixing vacuum leaks, cleaning or replacing the mass airflow sensor, or addressing issues with the fuel system.

8. Should I reset the OBDII code P0171 on my 2015 GMC Sierra after making repairs?

After making repairs to address code P0171 on a 2015 GMC Sierra, it is recommended to reset the code using an OBDII scanner to see if the issue has been resolved and to monitor for any recurring problems.

9. Is it safe to drive my 2015 GMC Sierra with OBDII code P0171?

While it may be possible to drive with code P0171 on a 2015 GMC Sierra for a short distance, it is advisable to address the issue promptly to prevent potential damage to the engine and emissions system.

10. How can regular maintenance help prevent OBDII code P0171 on a 2015 GMC Sierra?

Regular maintenance, such as replacing the air filter, checking for vacuum leaks, and ensuring proper fuel system operation, can help prevent issues like code P0171 on a 2015 GMC Sierra by maintaining optimal engine performance.