AutoCodes – Buick – P0174 Buick

P0174 Buick Code - Fuel Trim System Lean Bank 2

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: P0174 Buick indicates Fuel Trim System Lean Bank 2.
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.

Save to My Repairs Step-by-Step Diagnostic Guide My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 20,560

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 Aug 21, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0174 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 P0174 Buick - Fuel Trim System Lean Bank 2 - AutoCodes.com — P0174 Buick Code - Fuel Trim System Lean Bank 2

What does this mean?

What are the Possible Causes of the DTC P0174 Buick?

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

How to Fix the DTC P0174 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 P0174 code means that more air than gasoline is detected in the exhaust gases exiting the combustion chamber. If the P0174 is set in along with the P0171 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.

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 P0174

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0174 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 P0174 Buick code?

Need more information on how to fix the P0174 Buick code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0174 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 P0174 Buick Code

1. What are the common symptoms of OBDII code P0174 in a Buick, indicating a lean condition in the fuel trim system on bank 2?

- Common symptoms include rough idling, lack of power, poor fuel economy, and the illumination of the check engine light.

2. What are the potential causes of OBDII code P0174 in a Buick?

- Causes may include a vacuum leak, faulty oxygen sensor, clogged fuel filter, malfunctioning mass airflow sensor, or issues with the fuel injectors.

3. How can I diagnose the OBDII code P0174 in my Buick?

- Diagnose the code by checking for vacuum leaks, inspecting the oxygen sensor, testing the fuel pressure, examining the mass airflow sensor, and ensuring proper operation of the fuel injectors.

4. Can a dirty air filter trigger the OBDII code P0174 in a Buick?

- Yes, a dirty air filter can disrupt the air-fuel mixture ratio and contribute to a lean condition, potentially triggering the P0174 code.

5. What are some repair tips for addressing OBDII code P0174 in a Buick?

- Repair tips include fixing any vacuum leaks, replacing a faulty oxygen sensor, cleaning or replacing the air filter, ensuring proper fuel pressure, and addressing any issues with the mass airflow sensor.

6. Is it safe to continue driving my Buick with the OBDII code P0174 illuminated?

- It is not recommended to drive your Buick with the P0174 code for an extended period, as it can lead to engine damage and further issues. Seek diagnosis and repairs promptly.

7. Can a bad catalytic converter be a potential cause of OBDII code P0174 in a Buick?

- A failing catalytic converter can contribute to a lean condition, triggering the P0174 code. It is essential to inspect and replace a faulty catalytic converter if necessary.

8. Will resetting the check engine light resolve the OBDII code P0174 in my Buick?

- Simply resetting the check engine light will not fix the underlying issue causing the P0174 code. Proper diagnosis and repair are necessary to resolve the problem.

9. How can I prevent OBDII code P0174 from recurring in my Buick after repairs?

- Regular maintenance, such as replacing air filters and oxygen sensors at recommended intervals, inspecting for vacuum leaks, and using quality fuel, can help prevent the recurrence of the P0174 code.

10. Can a professional mechanic help diagnose and repair OBDII code P0174 in my Buick?

- Yes, a qualified mechanic with experience in diagnosing and repairing engine codes like P0174 can efficiently identify the issue and perform the necessary repairs to resolve the problem effectively.