AutoCodes – GMC – P0172 2017 GMC Sierra

P0172 2017 GMC Sierra Code - Fuel Trim System Rich 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 Faulty Mass Air Flow (MAF) Sensor, Intake Air Leaks, Exhaust Gas 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: P0172 2017 GMC Sierra indicates Fuel Trim System Rich Bank 1.
Common causes: Common causes include Dirty or Faulty Mass Air Flow (MAF) Sensor, Intake Air Leaks, Exhaust Gas 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 249

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 P0172 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 P0172 2017 GMC Sierra - Fuel Trim System Rich Bank 1 - AutoCodes.com — P0172 2017 GMC Sierra Code - Fuel Trim System Rich Bank 1

What does this mean?

What are the Possible Causes of the DTC P0172 2017 GMC Sierra?

Dirty or Faulty Mass Air Flow (MAF) Sensor
Intake Air Leaks
Exhaust Gas Leaks
Fuel Contamination
Faulty or Leaking Fuel Injectors
Faulty Front Heated Oxygen Sensor
Ignition Misfiring
Incorrect Fuel Pressure
Positive Crankcase Ventilation (PCV) Hose Leaks

How to Fix the DTC P0172 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 P0172 code means that more gasoline is detected in the exhaust gases exiting the combustion chamber. If the P0172 is set in along with the P0175 code, it is highly likely that the problem is caused by leaking fuel injectors. If there are no leaking fuel injectors, 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.

Click Here to Learn What is Bank 1 and Bank 2

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0172 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 P0172 2017 GMC Sierra Code

What does the OBDII code P0172 mean for a 2017 GMC Sierra?

P0172 indicates that the fuel mixture in Bank 1 is too rich, meaning there is excess fuel or insufficient air in the combustion process.

What are the common symptoms of code P0172 on a 2017 GMC Sierra?

Symptoms may include poor fuel economy, rough idling, black exhaust smoke, hesitation during acceleration, and possibly the check engine light.

What causes code P0172 on a 2017 GMC Sierra?

Common causes include a dirty or faulty mass airflow sensor (MAF), a malfunctioning oxygen sensor, a leaking fuel injector, excessive fuel pressure, or a clogged air filter.

Can a dirty air filter trigger code P0172?

Yes, a clogged or dirty air filter can restrict airflow to the engine, causing a rich fuel mixture and triggering code P0172.

How can a bad mass airflow sensor cause code P0172?

A faulty mass airflow sensor can provide incorrect airflow readings to the engine control module, leading to an overly rich fuel mixture.

How is code P0172 diagnosed on a 2017 GMC Sierra?

Diagnosis involves checking the air filter, inspecting the mass airflow sensor, testing the oxygen sensors, checking for fuel system leaks, and reviewing live data with an OBDII scanner.

Can driving with code P0172 damage the engine?

Driving with P0172 over an extended period can potentially damage the catalytic converter and reduce engine performance due to excessive fuel in the system.

How do you fix code P0172 on a 2017 GMC Sierra?

Repairs may include cleaning or replacing the mass airflow sensor, replacing the oxygen sensor, fixing fuel injector leaks, or replacing a clogged air filter.

Can P0172 be caused by bad fuel?

Yes, poor-quality or contaminated fuel can affect combustion and lead to a rich fuel mixture, triggering code P0172.

Is it safe to clear code P0172 without fixing the underlying issue?

Clearing the code without addressing the root cause may temporarily remove the check engine light, but the problem will likely return and could worsen over time.