AutoCodes – GMC – P0172 GMC

P0172 GMC 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 GMC 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 45,737

How popular is this code, among other codes? Medium

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 May 29, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P0172 GMC 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 GMC - Fuel Trim System Rich Bank 1 - AutoCodes.com — P0172 GMC Code - Fuel Trim System Rich Bank 1

What does this mean?

What are the Possible Causes of the DTC P0172 GMC?

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 GMC?

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

There is a Factory Service Bulletin for all 2000-2013 GMC models:
2000-2013 GMC Factory Service Bulletin OBDII Code P0172

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0172 GMC 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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Information for Specific GMC Models

P0172 2014 GMC Sierra — Fuel Trim System Rich Bank 1
P0172 2015 GMC Sierra — Fuel Trim System Rich Bank 1
P0172 2016 GMC Sierra — Fuel Trim System Rich Bank 1
P0172 2017 GMC Sierra — Fuel Trim System Rich Bank 1
P0172 2018 GMC Sierra — Fuel Trim System Rich Bank 1

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 GMC Code

1. What does OBDII code P0172 GMC indicate?

- The code P0172 indicates that the fuel trim system on bank 1 is detecting a rich condition, meaning there is too much fuel in the air-fuel mixture.

2. What are the common symptoms of a P0172 code in a GMC vehicle?

- Common symptoms include reduced fuel efficiency, a rough idle, engine hesitation, black smoke from the exhaust, and a noticeable gasoline smell.

3. What are the possible causes of a P0172 code in a GMC vehicle?

- The common causes of a P0172 code include a faulty oxygen sensor, a dirty or clogged fuel injector, a vacuum leak, a malfunctioning mass airflow sensor, or a problem with the fuel pressure regulator.

4. How can I diagnose a P0172 code in my GMC vehicle?

- You can diagnose a P0172 code by performing a visual inspection of the engine components, checking for vacuum leaks, testing the oxygen sensor, inspecting the fuel injectors, and using a scan tool to monitor fuel trim data.

5. How do I repair a P0172 code in my GMC vehicle?

- Repair methods for a P0172 code may include replacing a faulty oxygen sensor, cleaning or replacing clogged fuel injectors, fixing any vacuum leaks, cleaning the mass airflow sensor, or addressing issues with the fuel pressure regulator.

6. Can a dirty air filter cause a P0172 code in a GMC vehicle?

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

7. Is it safe to drive with a P0172 code in a GMC vehicle?

- It is not recommended to drive with a P0172 code as it can lead to poor engine performance, increased emissions, and potential damage to the catalytic converter.

8. How much does it cost to repair a P0172 code in a GMC vehicle?

- The cost of repairing a P0172 code can vary depending on the specific cause of the issue, but it may range from $100 to $500 or more, including parts and labor.

9. Can a P0172 code be triggered by a bad fuel pump in a GMC vehicle?

- Yes, a failing fuel pump can disrupt the fuel delivery to the engine, causing a rich fuel mixture and potentially triggering a P0172 code.

10. Will a P0172 code reset itself after the issue is fixed in a GMC vehicle?

- In some cases, the P0172 code may reset itself after the underlying issue is repaired. However, it is recommended to use a scan tool to clear the code manually and ensure the problem has been resolved.