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P0172 Buick 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 Buick 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 55,264
How popular is this code, among other codes? Medium
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Table of contents Created and updated by William Orellana on May 29, 2022
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Code P0172 Buick 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 Buick - Fuel Trim System Rich Bank 1 - AutoCodes.com
P0172 Buick Code - Fuel Trim System Rich Bank 1
What does this mean?

What are the Possible Causes of the DTC P0172 Buick?

  • 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 Buick?

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 Buick models:
2000-2013 Buick Factory Service Bulletin OBDII Code P0172

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0172 Buick 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 Buick code?

Need more information on how to fix the P0172 Buick code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0172 Buick code diagnosed by a professional: Find a repair shop in your area

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 Buick Code

1. What does OBDII code P0172 for Buick mean?

- OBDII code P0172 indicates that the fuel trim system on Bank 1 is detecting a rich condition, meaning there is too much fuel compared to air in the engine's air-fuel mixture.

2. What are the common symptoms of OBDII code P0172 in a Buick?

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

3. What are the potential causes of OBDII code P0172 in a Buick?

- Common causes include a faulty oxygen sensor, a dirty or clogged fuel injector, a vacuum leak, a malfunctioning mass airflow sensor, a fuel pressure regulator issue, or a problem with the engine's computer system.

4. How can I diagnose the OBDII code P0172 in my Buick?

- Diagnosing P0172 may involve checking the oxygen sensor readings, inspecting the fuel injectors, looking for vacuum leaks, testing the mass airflow sensor, and verifying the fuel pressure regulator's functionality.

5. Can I drive my Buick with an OBDII code P0172?

- It is not recommended to drive your Buick with an unresolved P0172 code, as it can lead to engine damage and other issues. It's best to address the problem promptly.

6. How can I repair OBDII code P0172 in my Buick?

- Repair options may include replacing the oxygen sensor, cleaning or replacing fuel injectors, fixing vacuum leaks, replacing the mass airflow sensor, addressing the fuel pressure regulator, or resetting the engine's computer system.

7. Will resetting the OBDII code P0172 on my Buick make it go away permanently?

- Resetting the code may temporarily turn off the check engine light, but if the underlying issue causing P0172 is not fixed, the code is likely to return.

8. How much does it cost to fix OBDII code P0172 in a Buick?

- The cost of fixing P0172 can vary depending on the specific cause of the issue. It's recommended to get a diagnosis from a mechanic to determine the exact repair cost.

9. Can a dirty air filter cause OBDII code P0172 in a Buick?

- A dirty air filter can contribute to a rich air-fuel mixture, potentially leading to a P0172 code. It's important to regularly replace the air filter as part of routine maintenance.

10. How often should I have my Buick's fuel system inspected to prevent OBDII code P0172?

- It's advisable to have your Buick's fuel system inspected during regular maintenance intervals or whenever you notice symptoms of a potential issue to help prevent the occurrence of OBDII code P0172.

Discuss the causes and fixes for P0172 Buick OBDII Code

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  • P0172 code on a buick lesabre 04 3800 engine, 106000 miles, needs inspection, starts and runs fine, idles a little rough when cold for 10 seconds then smooths out. I have a solus engine tool and it says ltft-25, stft at idle can be -9 , 1500 rpm stft goes to 0 - 1 or so. Wot will bring ltft to -22. The O2 sensor is swinging 150 to 890. When you snap the gas peddle the O2 sensor goes to 890 and down to 60. The maf is a new reman from advance auto . From what I've read it's reading correctly for the rpms .ect we have done these things in the last 8 mos, upper and lower intake manifold gaskets, front O2 sensor , ait, tps, catalytic converter, thermostat, coolant temp sensor, plugs and wires, all new coils , new ecm, new battery, idle control, map sensor, I'm going to lose my mind!

    Reply to Comment

  • I have similar problem

    Reply to Comment

  • What model and year is your vehicle?

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  • I have a 2012 Buick verano p0172 code short-term fuel trim is a -3.9% long-term fuel trim bank one is -25.7% fuel pressure is 57.8 PSI map is .33 pounds a minute I have replaced air filter replacement mass air flow sensor have checked for vacuum leaks no smoke test though I have replaced spark plugs O2 sensors and only thing I have not done is fuel injectors oh yeah fuel pressure is at 57.8 I already said that sorry anyway does not seem to have hesitation maybe slightly and does not have a loss of power but seems to be dumping a little bit of excess fuel in the oilI've had this code for like a year now trying to troubleshoot all this and change everything out can I get some input for backyard trade shade tree mechanic anything is really appreciate it

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  • I apologize for the late response. Although you have good fuel pressure, you could have clogged fuel injectors. I recommend using high octane gas, and if possible, fuel additive for a few weeks to clean the fuel injectors. There is a factory service bulletin for the same problem, but they recommend a dealer only tool and cleaners to clean the fuel injectors.

    Here is a link to the bulletin: https://f01.justanswer.com/...

    Reply to Comment
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