P0174 Code: What It Means and How to Fix Lean Engine Issues in Ford Cars

P0174 Code: What It Means and How to Fix Lean Engine Issues in Ford Cars

P0174 code, it specifically indicates a lean condition on the second bank of the engine, which can be caused by various factors such as vacuum leaks, faulty MAF sensors, or fuel system issues.

What is the P0174 Code?

The OBD-II P0174 code stands for “System Too Lean (Bank 2).” This code is triggered when the engine control module (ECM) detects that the air-fuel mixture is too lean on the second bank of the engine. Essentially, there’s too much air and not enough fuel in the combustion process.

Commonly Affected Ford Models

The P0174 code can appear in a variety of Ford models. Here are some of the most commonly affected:

  • Ford F-150
  • Ford Explorer
  • Ford Expedition
  • Ford Escape
  • Ford Mustang
  • Ford Taurus
  • Ford Edge
  • Ford Fusion

Implications for Vehicle Performance and Emissions

A P0174 code can have several implications for your vehicle’s performance and emissions:

  • Engine Performance: A lean condition can cause rough idling, hesitation during acceleration, and overall poor engine performance.
  • Fuel Efficiency: The engine may run less efficiently, leading to decreased fuel economy.
  • Increased Emissions: A lean air-fuel mixture can result in higher emissions, potentially causing your vehicle to fail an emissions test.
  • Engine Damage: Prolonged lean conditions can lead to engine damage due to overheating and detonation (knocking).

Diagnosing the P0174 Code

Diagnosing the root cause of the P0174 code involves several steps. Here’s a comprehensive guide to help you through the process:

  1. OBD-II Scanner: Use an OBD-II scanner to confirm the P0174 code and check for any additional codes that might indicate related issues.
  2. Inspect for Vacuum Leaks: Check for any vacuum leaks in hoses, intake manifold gaskets, and the PCV system. Leaks can cause unmetered air to enter the engine.
  3. Examine the Mass Air Flow (MAF) Sensor: A dirty or faulty MAF sensor can send incorrect readings to the ECM, leading to a lean condition.
  4. Check the Fuel System: Ensure that the fuel pump, fuel filter, and fuel injectors are functioning correctly and delivering the proper amount of fuel.
  5. Inspect the Oxygen Sensors: Faulty or aging oxygen sensors can send incorrect data to the ECM, causing it to lean out the air-fuel mixture.

Symptoms and Solutions

Key Symptoms

  • Check engine light is on
  • Rough idling
  • Hesitation or stumbling during acceleration
  • Poor fuel economy
  • Engine misfires


  • Fix Vacuum Leaks: Repair or replace any leaking hoses, gaskets, or PCV components.
  • Clean or Replace the MAF Sensor: Ensure the MAF sensor is clean and functioning correctly. Replace if necessary.
  • Fuel System Maintenance: Check and replace the fuel filter if it’s clogged. Ensure the fuel pump and injectors are operating correctly.
  • Replace Oxygen Sensors: If the oxygen sensors are faulty or have high mileage, replace them to ensure accurate readings.
  • Inspect and Clean the Throttle Body: A dirty throttle body can also cause lean conditions. Clean it thoroughly if needed.

Frequently Asked Questions (FAQ)

Q1: Is it safe to drive with the P0174 code?
A: While it may be safe to drive for short distances, it’s not advisable to ignore this code. Prolonged driving with a lean condition can lead to engine damage and increased emissions.

Q2: What are the potential repair costs?
A: Repair costs can vary depending on the exact cause. Simple fixes like replacing a vacuum hose might cost $50-$100, while replacing the MAF sensor or oxygen sensors can range from $200-$400.

Q3: How can I prevent the P0174 code in the future?
A: Regular maintenance is key. Keep your engine’s air and fuel systems clean, replace filters as needed, and check for vacuum leaks periodically.


Addressing the P0174 code promptly is crucial for maintaining your Ford’s efficiency, performance, and compliance with emission standards. By understanding what this code means and following the steps to diagnose and fix the issue, you can keep your vehicle running smoothly. Regular maintenance and early detection are essential in preventing such issues from arising. Remember, taking care of your vehicle ensures its longevity and your safety on the road. Happy driving!

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