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AutoCodes – GMC – P0172 2015 GMC Sierra

P0172 2015 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 2015 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 358
How popular is this code, among other codes? Low
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Table of contents Created and updated by William Orellana on Jul 23, 2023
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Code P0172 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 P0172 2015 GMC Sierra - Fuel Trim System Rich Bank 1 - AutoCodes.com
P0172 2015 GMC Sierra Code - Fuel Trim System Rich Bank 1
What does this mean?

What are the Possible Causes of the DTC P0172 2015 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 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 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 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.

Need more information about the P0172 2015 GMC Sierra code?

Need more information on how to fix the P0172 2015 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 P0172 2015 GMC Sierra Code

1. What does the OBDII code P0172 mean on a 2015 GMC Sierra?

P0172 indicates that the engine's fuel mixture is too rich (too much fuel and not enough air) on Bank 1, which is the side of the engine containing cylinder 1.

2. What are the common symptoms of P0172 on a 2015 GMC Sierra?

Symptoms include poor fuel economy, black smoke from the exhaust, rough idle, hesitation during acceleration, and an illuminated Check Engine Light.

3. What causes the P0172 code on a 2015 GMC Sierra?

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

4. Can a dirty air filter cause the P0172 code on a 2015 GMC Sierra?

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

5. How do I fix the P0172 code on my 2015 GMC Sierra?

Repair steps include inspecting and cleaning the MAF sensor, replacing the air filter, checking for fuel injector leaks, verifying fuel pressure, and replacing faulty oxygen sensors if needed.

6. Is it safe to drive my 2015 GMC Sierra with the P0172 code?

Driving with the P0172 code is not recommended as it can lead to poor performance, increased emissions, and potential damage to the catalytic converter.

7. Can a malfunctioning mass air flow (MAF) sensor cause the P0172 code on a 2015 GMC Sierra?

Yes, a dirty or faulty MAF sensor can miscalculate the amount of air entering the engine, leading to an overly rich fuel mixture and triggering the P0172 code.

8. How can I diagnose the P0172 code on a 2015 GMC Sierra?

Start by scanning for additional codes, inspecting the air intake system, checking fuel injectors for leaks, testing the MAF sensor, and monitoring oxygen sensor readings with a diagnostic tool.

9. Can a vacuum leak cause the P0172 code on a 2015 GMC Sierra?

No, a vacuum leak typically causes a lean condition rather than a rich condition. P0172 is more likely caused by excess fuel or restricted airflow.

10. What is Bank 1 in the context of the P0172 code on a 2015 GMC Sierra?

Bank 1 refers to the side of the engine containing cylinder 1. On a V8 engine like the GMC Sierra’s, it is typically the driver’s side.

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