AutoCodes – Generic – P0174

P0174 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 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.

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Code Popularity 114,997

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 Jul 23, 2023

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P0174 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 - Fuel Trim System Lean Bank 2 - AutoCodes.com — P0174 Code - Fuel Trim System Lean Bank 2

What does this mean?

What are the Possible Causes of the DTC P0174?

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?

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.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0174 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 Makes

P0174 Acura — Fuel System Too Lean Bank 2
P0174 Audi — System Too Lean Bank 2
P0174 BMW — Mixture Control 2 System Too Lean Bank 2
P0174 Buick — Fuel Trim System Lean Bank 2
P0174 Cadillac — Fuel Trim System Lean Bank 2
P0174 Chevrolet — Fuel Trim System Lean Bank 2
P0174 Chrysler — Fuel System 2/1 Lean
P0174 Dodge — Fuel System 2/1 Lean
P0174 Ford — Fuel Injection System Too Lean Bank 2
P0174 GMC — Fuel Trim System Lean Bank 2
P0174 Honda — Fuel System Too Lean Bank 2
P0174 Hummer — Fuel Trim System Lean Bank 2
P0174 Hyundai — System Too Lean Bank 2
P0174 Infiniti — Fuel Injection System Too Lean Bank 2
P0174 Jaguar — System Too Lean Bank 2
P0174 Jeep — Fuel System 2/1 Lean
P0174 KIA — Bank 2 System Too Lean
P0174 Land Rover — System Too Lean Bank 2
P0174 Lexus — Fuel Trim System Too Lean Bank 2
P0174 Lincoln — Fuel Injection System Too Lean Bank 2
P0174 Mazda — Lean Air/Fuel Ratio Bank 2
P0174 Mercedes-Benz — System Too Lean Bank 2
P0174 Mercury — Fuel Injection System Too Lean Bank 2
P0174 MINI — Mixture Control 2 System Too Lean Bank 2
P0174 Mitsubishi — System Too Lean Cylinders 2-3
P0174 Nissan — Fuel Injection System Too Lean Bank 2
P0174 Oldsmobile — Fuel Trim System Lean Bank 2
P0174 Pontiac — Fuel Trim System Lean Bank 2
P0174 Saturn — Fuel Trim System Lean Bank 2
P0174 Scion — Fuel Trim System Too Lean Bank 2
P0174 Subaru — System Too Lean Bank 2
P0174 Suzuki — Fuel Trim System Lean Bank 2
P0174 Toyota — Fuel Trim System Too Lean Bank 2
P0174 Volkswagen — System Too Lean Bank 2

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 Code

1. What are the common symptoms of OBDII code P0174 (Fuel Trim System Lean Bank 2)?

- Common symptoms include rough idle, loss of power, engine hesitation, and increased fuel consumption.

2. What are the possible causes of OBDII code P0174?

- Possible causes include a vacuum leak, faulty oxygen sensor, clogged fuel filter, malfunctioning mass airflow sensor, or a problem with the fuel injectors.

3. How can I diagnose the root cause of OBDII code P0174?

- You can start by checking for vacuum leaks, inspecting the oxygen sensor, testing the fuel pressure, cleaning or replacing the mass airflow sensor, and examining the fuel injectors for any issues.

4. How serious is OBDII code P0174 (Fuel Trim System Lean Bank 2)?

- While the vehicle may still be drivable with this code, it can lead to poor performance and reduced fuel efficiency. Ignoring the issue can potentially cause damage to the engine or emissions system over time.

5. Can a dirty or clogged air filter trigger OBDII code P0174?

- Yes, a dirty or clogged air filter can disrupt the air-fuel mixture and contribute to a lean condition, which may trigger code P0174.

6. Is it safe to continue driving with OBDII code P0174 present?

- It is not recommended to drive for an extended period with this code as it can lead to engine damage or affect the catalytic converter if left unresolved.

7. How can I reset OBDII code P0174 after making repairs?

- You can reset the code using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes. However, the code will reappear if the underlying issue is not fixed.

8. Will OBDII code P0174 cause the check engine light to illuminate?

- Yes, code P0174 will trigger the check engine light to come on to alert you of a potential issue with the fuel trim system on bank 2.

9. Are there any DIY repair tips for addressing OBDII code P0174?

- DIY repair tips include checking for loose or damaged vacuum hoses, inspecting the air intake system for leaks, and ensuring the oxygen sensor is functioning correctly.

10. Can a faulty fuel pump be a possible cause of OBDII code P0174?

- Yes, a failing fuel pump can lead to insufficient fuel delivery, causing a lean condition on bank 2 and triggering code P0174.