AutoCodes – GMC – P0171 2017 GMC Sierra

P0171 2017 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 2017 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 441

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 2017 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 2017 GMC Sierra - Fuel Trim System Lean Bank 1 - AutoCodes.com — P0171 2017 GMC Sierra Code - Fuel Trim System Lean Bank 1

What does this mean?

What are the Possible Causes of the DTC P0171 2017 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 2017 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 2017 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 2017 GMC Sierra Code

1. What does the OBDII code P0171 on a 2017 GMC Sierra mean?

The code P0171 indicates a "Fuel Trim System Lean Bank 1" fault, which means that the engine is detecting a lean air-to-fuel mixture in the cylinders of bank 1.

2. What are the common symptoms of a P0171 code on a 2017 GMC Sierra?

Common symptoms include rough idle, poor acceleration, hesitation, engine misfires, stalling, and in some cases, the check engine light may illuminate.

3. What are the possible causes of a P0171 code on a 2017 GMC Sierra?

Common causes include a vacuum leak, faulty oxygen sensor, fuel system issues, intake air leaks, a dirty or clogged fuel injector, a malfunctioning mass airflow sensor, or a faulty PCV valve.

4. How can I diagnose a P0171 code on a 2017 GMC Sierra?

Diagnosis involves checking for vacuum leaks, inspecting the air intake system, testing the oxygen sensor, examining the fuel pressure and injectors, and ensuring there are no exhaust leaks.

5. Can a dirty air filter trigger a P0171 code on a 2017 GMC Sierra?

Yes, a dirty or clogged air filter can disrupt the air-to-fuel mixture ratio and potentially trigger a P0171 code due to inadequate airflow.

6. How serious is a P0171 code on a 2017 GMC Sierra?

While the vehicle may still be operable with a P0171 code, it is not recommended to ignore it as it can lead to long-term engine damage and decreased fuel efficiency if left unresolved.

7. How can I repair a P0171 code on a 2017 GMC Sierra?

Repair options include fixing any vacuum leaks, replacing the oxygen sensor, cleaning or replacing the mass airflow sensor, checking and cleaning the fuel injectors, and ensuring the air intake system is sealed properly.

8. Can a P0171 code be triggered by using poor-quality fuel in a 2017 GMC Sierra?

Yes, using poor-quality fuel with inadequate octane levels can affect the air-to-fuel mixture and potentially lead to a lean condition triggering the P0171 code.

9. Is it safe to continue driving with a P0171 code on a 2017 GMC Sierra?

It is not recommended to drive for an extended period with a P0171 code, as it can lead to engine performance issues and potential damage over time. It is best to address the issue promptly.

10. How much does it typically cost to repair a P0171 code on a 2017 GMC Sierra?

The cost of repairs for a P0171 code can vary depending on the root cause of the issue. Costs may range from a simple fix like tightening a loose hose to more involved repairs like replacing sensors or components, potentially costing a few hundred dollars to resolve.