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P0171: System Too Lean (Bank 1)

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    This story was created with generative AI and was reviewed and fact-checked by our staff of editors and experts.
    edited by
    Director, Editorial Content
    Steven Ewing has worked in the automotive industry since 2003. In that time, he's written thousands of car-related articles and tested just as many vehicles. Steven is Edmunds' director of editorial content and has previously been on staff at Winding Road magazine, Autoblog, Motor1.com, CNET Roadshow, and was the U.S. correspondent for Top Gear magazine. Steven has also contributed to Automobile magazine, Ars Technica, Car and Driver, The Drive, Jalopnik, SlashGear, and dozens of other publications. In his spare time, Steven loves to play the drums, cook, and lust over small JDM cars that never made it to the States.

What does the P0171 error code mean?

The P0171 error code occurs when sensors detect too much oxygen in the exhaust system, indicating that the engine is running with a lean fuel mixture. The "Bank 1" designation refers to the side of the engine that contains the first cylinder. A lean condition means the engine is receiving too much air, too little fuel, or a combination of both.

Why is the P0171 issue important?

Running too lean can result in poor fuel economy, increased emissions, or potential engine damage over time. Addressing this issue promptly can prevent more serious problems and costly repairs in the future.

Can I safely drive my car with this error code?

While it may be possible to drive a vehicle with a P0171 error code for a short period, it's not advisable. Driving with a lean fuel mixture can lead to significant engine problems, such as misfires, rough idle and, in severe cases, engine overheating. If you notice this error, it's best to have the vehicle checked by a professional mechanic as soon as possible.

Common symptoms associated with the P0171 error code

  • Check engine light is on
  • The engine runs rough or idles poorly
  • Decreased fuel efficiency
  • Engine misfires
  • A noticeable lack of power or hesitation during acceleration

Diagnosing the P0171 error code

Mechanics typically start by checking the vehicle's fuel system for leaks, clogs or malfunctioning components that could be allowing excess air into the system. They will also inspect the oxygen sensors and mass airflow sensor for proper operation because these sensors play a crucial role in determining the air-fuel mixture. A vacuum leak is another common cause, so hoses and gaskets are carefully examined for any signs of wear or damage.

Repairing the P0171 error code

Repairing a P0171 error code varies depending on the underlying cause. Common repairs include:

  • Replacing faulty oxygen sensors or mass airflow sensors
  • Repairing or replacing leaking hoses or gaskets
  • Cleaning or replacing clogged fuel injectors
  • Adjusting the fuel pressure to proper levels

Each repair aims to restore the proper balance of air and fuel to the engine, ensuring it runs efficiently and safely. It's essential to address this error code promptly to maintain vehicle performance and prevent further damage.

Edmunds.comby

This story was created with generative AI and was reviewed and fact-checked by our staff of editors and experts.

Steven Ewingedited by

Steven Ewing has worked in the automotive industry since 2003. In that time, he's written thousands of car-related articles and tested just as many vehicles. Steven is Edmunds' director of editorial content and has previously been on staff at Winding Road magazine, Autoblog, Motor1.com, CNET Roadshow, and was the U.S. correspondent for Top Gear magazine. Steven has also contributed to Automobile magazine, Ars Technica, Car and Driver, The Drive, Jalopnik, SlashGear, and dozens of other publications. In his spare time, Steven loves to play the drums, cook, and lust over small JDM cars that never made it to the States.

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