P0174 Fuel Trim Malfunction (Bank 2)

Understanding P0174 Fuel Trim Malfunction

P0174 is an error code in your vehicle’s diagnostic system indicating a fuel trim malfunction in the second bank of your engine. But what does that mean? In simple terms, your engine isn’t getting the right mix of air and fuel, which can lead to a range of issues if not addressed promptly.

Causes of P0174 Fuel Trim Malfunction

There are several potential causes of a P0174 error code. Some of the most common include a vacuum leak, faulty fuel injectors, or a malfunctioning mass airflow sensor. More rarely, this issue can be caused by a failing oxygen sensor or an improperly sealed fuel cap.

Symptoms of P0174 Fuel Trim Malfunction

Recognizing the symptoms of a P0174 fuel trim malfunction can help you address the problem before it causes serious damage. Symptoms may include a decrease in fuel efficiency, difficulty starting the vehicle, or a rough idle. In some cases, you may even notice a lack of power when accelerating.

Diagnosing P0174 Fuel Trim Malfunction

Tools Required

To diagnose a P0174 error code, you’ll need an OBD-II scanner. This is a device that can read and interpret the codes generated by your vehicle’s diagnostic system.

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Step by Step Process

First, connect your OBD-II scanner to the vehicle and read the codes. If P0174 is present, it’s time to start troubleshooting. Check for visible signs of damage to the fuel system components, and consider running a smoke test to check for vacuum leaks.

Fixing P0174 Fuel Trim Malfunction

Common Fixes

In many cases, fixing a P0174 error code can be as simple as replacing a faulty fuel injector or mass airflow sensor. If a vacuum leak is the cause, it may involve repairing or replacing damaged hoses.

What to Do if the Code Returns

If the P0174 code returns after you’ve made repairs, it’s time to consider more serious issues. You may need to replace the oxygen sensor, or there could be a problem with the engine control module.

Preventing P0174 Fuel Trim Malfunction

Regular Vehicle Maintenance

The best way to prevent a P0174 error code is through regular vehicle maintenance. This includes regular oil changes and replacing components like the fuel filter and spark plugs as recommended by your vehicle’s manufacturer.

Importance of Quality Fuel

Using good quality fuel can also help prevent P0174. Poor quality fuel can lead to build-up in the fuel system, which can cause a range of issues, including a P0174 error code.

Impact of Oxygen Sensors

Your vehicle’s oxygen sensors play a critical role in maintaining the correct fuel mixture. A failing oxygen sensor can lead to a P0174 code. Regular check-ups can help to identify and rectify any issues with the sensors.


Understanding the cause and symptoms of a P0174 Fuel Trim Malfunction can save you from expensive repairs down the line. Regular vehicle maintenance and the use of quality fuel are the best ways to prevent this issue. However, if you do encounter this problem, having it diagnosed and fixed promptly will ensure the longevity and performance of your vehicle.


1. What does ‘Bank 2’ mean in P0174 Fuel Trim Malfunction (Bank 2)?

‘Bank 2’ refers to the side of the engine that does not contain cylinder 1 in a V-configured engine.

2. Can I drive my car with a P0174 code?

While you may be able to drive with a P0174 code, it’s not recommended as it can lead to more serious damage to your vehicle over time.

3. How do I know if I have a vacuum leak?

Symptoms of a vacuum leak may include a rough idle, high RPMs, and poor fuel economy.

4. How often should I replace my oxygen sensors?

Generally, oxygen sensors should be replaced every 60,000 to 90,000 miles. However, it’s best to refer to your vehicle’s owner’s manual for specific recommendations.

5. Can poor quality fuel cause a P0174 code?

Yes, poor quality fuel can lead to deposits in the fuel system, which can ultimately result in a P0174 code.