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P0174 Fault Code: What It Means And How to Fix It

P0174 is a fault code that indicates a lean condition on Bank 2 of the engine.

AFR Air to fuel ratio infographic

The term “lean” refers to a condition where the air-to-fuel ratio is higher than it should be, meaning that there is too much air in relation to the amount of fuel being delivered to the engine.

This can lead to a variety of symptoms, including poor fuel economy, rough idling, lack of power, and the check engine light illuminating.

I’m John Cunningham, a qualified mechanic, you are in the right place, and very shortly, you’ll have a good understanding of the cause, the diagnosis process, and the fix.

On this page, we’ll cover the following:

P0174 Possible causes

There are many possible causes of a lean condition on Bank 2, including a faulty oxygen sensor, clogged fuel filter, dirty air filter, vacuum leaks, or a malfunctioning fuel pressure regulator. A lean condition can also be caused by a failing catalytic converter, which can cause the oxygen sensor to read falsely high levels of oxygen in the exhaust.

P0174 Diagnosis

To diagnose P0174, a mechanic will typically use an OBD-II scanner or code reader to check for fault codes, and then perform a visual inspection of the engine, fuel system, air intake system, and exhaust system.

A mechanic may also perform a fuel pressure test or check the oxygen sensor readings to determine the underlying cause of the lean condition.

Fixing P0174

Fixing P0174 usually involves replacing or repairing the faulty component that is causing the lean condition. This may include replacing the oxygen sensor, cleaning or replacing the air filter, checking for and repairing any vacuum leaks, replacing the fuel filter, or replacing a malfunctioning fuel pressure regulator.

In some cases, the catalytic converter may need to be replaced if it is causing the oxygen sensor to read falsely high oxygen levels.

About the Author

This article was created with the assistance of AI technology to aid the author, John Cunningham, who is a seasoned Red Seal-certified auto technician with more than 25 years of experience in vehicle repairs. However, please note that John Cunningham has edited the content to ensure accuracy and quality.

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