Engine-CodesHummer – P0174 Hummer

P0174 Hummer Code - Fuel Trim System Lean Bank 2

Quick Answer

The P0174 diagnostic trouble code (DTC) for Hummer vehicles indicates a fuel trim system lean condition on bank 2 of the engine. Common causes include Vacuum leak, Faulty oxygen sensor, Fuel delivery issues. 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 Hummer indicates Fuel Trim System Lean Bank 2.
Common causes
Common causes include Vacuum leak, Faulty oxygen sensor, Fuel delivery issues.
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.
Table of contents Created and updated by William Orellana on Sep 12, 2024
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Code P0174 Hummer Description

The P0174 diagnostic trouble code (DTC) for Hummer vehicles indicates a fuel trim system lean condition on bank 2 of the engine. This means that the engine control module (ECM) has detected that the air-fuel mixture is too lean on the second bank of cylinders. The fuel trim system is responsible for adjusting the air-fuel mixture to maintain optimal combustion efficiency. When the system detects a lean condition, it means that there is too much air and not enough fuel in the mixture, which can lead to poor engine performance and increased emissions.

OBDII Code P0174 Hummer - Fuel Trim System Lean Bank 2
P0174 Hummer Code - Fuel Trim System Lean Bank 2

Common Causes of P0174 Hummer

  1. Vacuum leak
  2. Faulty oxygen sensor
  3. Fuel delivery issues
  4. Clogged fuel injectors
  5. Malfunctioning mass airflow sensor

Symptoms of P0174 Hummer

  1. Rough idle
  2. Engine hesitation
  3. Decreased fuel efficiency
  4. Check Engine Light illuminated
  5. Engine misfires

How to Fix P0174 Hummer

  1. Diagnose the specific cause of the lean condition using a scan tool to monitor fuel trims and oxygen sensor readings.
  2. Inspect for vacuum leaks by visually inspecting hoses and connections, and using a smoke machine to detect leaks.
  3. Test the oxygen sensor for proper operation and replace if necessary.
  4. Clean or replace clogged fuel injectors to ensure proper fuel delivery.
  5. Inspect and clean the mass airflow sensor or replace if faulty.

Cost to Fix P0174 Hummer

The cost of repairing a P0174 code on a Hummer can vary depending on the specific cause of the lean condition and the labor rates in your area. Typically, the cost of parts for this repair can range from $100 to $500, with labor costs adding an additional $100 to $300. Overall, you can expect to pay between $200 and $800 for this repair. It is recommended to consult with a qualified mechanic to get an accurate estimate based on your vehicle's make and model.

Tech Notes for P0174 Hummer

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 the following HUMMER models:

2003-2008 HUMMER H2

2006-2008 HUMMER H3

2003-2008 HUMMER Factory Service Bulletin OBDII Code P0174

Need more information about the P0174 Hummer code?

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

Need Help with the Code?

Get the P0174 Hummer 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 Hummer Code

1. What are the common symptoms of OBDII code P0174 in a Hummer?

- Common symptoms include rough idling, engine hesitation, loss of power, increased fuel consumption, and the illumination of the check engine light.

2. What does the OBDII code P0174 indicating a "Fuel Trim System Lean Bank 2" mean in a Hummer?

- This code indicates that the engine control module has detected a lean condition in the fuel mixture on bank 2 of the engine, which can lead to drivability issues.

3. What are the possible causes of OBDII code P0174 in a Hummer?

- Common causes include a vacuum leak, faulty oxygen sensor, fuel delivery issues, intake air leaks, clogged fuel injectors, or a malfunctioning mass airflow sensor.

4. How can I diagnose the OBDII code P0174 in my Hummer?

- Diagnosing this code typically involves inspecting for vacuum leaks, testing oxygen sensors, checking fuel pressure, examining intake components, and using a scan tool to monitor fuel trims.

5. Can driving with OBDII code P0174 in a Hummer cause further damage?

- Continuing to drive with this code may lead to decreased fuel efficiency, potential damage to the catalytic converter, and ultimately affect the engine's performance.

6. How can I repair OBDII code P0174 in my Hummer?

- Repair options may include fixing vacuum leaks, replacing faulty oxygen sensors, cleaning or replacing fuel injectors, addressing intake air leaks, and ensuring proper fuel delivery.

7. Is it safe to reset the check engine light after repairing OBDII code P0174 in a Hummer?

- Yes, it is safe to reset the check engine light after repairing the issue. However, it is recommended to confirm that the problem has been resolved before doing so.

8. How long does it take to fix OBDII code P0174 in a Hummer?

- The time needed to fix this code can vary depending on the specific cause. Simple repairs like fixing a vacuum leak may take a short time, while diagnosing and replacing faulty components can take longer.

9. Should I attempt to repair OBDII code P0174 in my Hummer myself?

- If you have the necessary tools, experience, and knowledge, you can attempt to repair this code yourself. Otherwise, it may be best to consult a professional mechanic for accurate diagnosis and repair.

10. Will OBDII code P0174 cause my Hummer to fail an emissions test?

- Yes, if left unresolved, OBDII code P0174 can cause your Hummer to fail an emissions test due to the lean fuel mixture affecting emissions levels.

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