P1171 Code - Fuel System Lean During Acceleration

Quick Answer

The P1171 diagnostic trouble code indicates that the fuel system is running lean during acceleration. Common causes include Clogged fuel injectors, Dirty or failing fuel filter, Vacuum leak in the intake system. 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

P1171 indicates Fuel System Lean During Acceleration.

Common causes

Common causes include Clogged fuel injectors, Dirty or failing fuel filter, Vacuum leak in the intake system.

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.

• Description
• Common Causes
• Symptoms
• How To Fix
• Cost to Fix
• FAQs
• Comments
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Common Causes of P1171

Symptoms of P1171

How to Fix P1171

Cost to Fix P1171

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Code P1171 Information for Specific Makes

• P1171 Acura — Fuel System Lean During Acceleration
• P1171 Audi — Throttle Actuation Potentiometer Signal 2 Range/Performance
• P1171 BMW — Ambient Pressure Sensor Learned Value Error
• P1171 Buick — Fuel System Lean During Acceleration
• P1171 Cadillac — Fuel System Lean During Acceleration
• P1171 Chevrolet — Fuel System Lean During Acceleration
• P1171 Ford — Rotor Sensor Fault
• P1171 GMC — Fuel System Lean During Acceleration
• P1171 Honda — Fuel System Lean During Acceleration
• P1171 Hyundai — Electronic Throttle System Open
• P1171 Isuzu — Fuel System Lean During Acceleration
• P1171 Land Rover — LH Bank Lambda Control Adaption Over Time Too Large
• P1171 MINI — Ambient Pressure Sensor Learned Value Error
• P1171 Suzuki — Fuel Supply System Lean During Power Enrichment
• P1171 Volkswagen — Throttle Actuation Potentiometer Signal 2 Range/Performance
• P1171 Volvo — Long Term Fuel Trim

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 P1171 Code

1. What are the common symptoms of OBDII code P1171 (Fuel System Lean During Acceleration)?

- Common symptoms include rough idling, hesitation or stumbling during acceleration, poor fuel economy, and potential engine misfires.

2. What are the possible causes of OBDII code P1171?

- The code P1171 can be triggered by issues such as a vacuum leak, faulty oxygen sensor, clogged fuel filter, malfunctioning fuel injectors, or a problem with the Mass Air Flow (MAF) sensor.

3. How can I diagnose the source of the lean fuel mixture indicated by code P1171?

- You can start by checking for any visible signs of a vacuum leak, inspecting the oxygen sensor for proper function, testing the fuel pressure, cleaning or replacing the fuel filter, and ensuring the MAF sensor is working correctly.

4. Can a dirty or clogged air filter cause OBDII code P1171?

- Yes, a dirty or clogged air filter can restrict airflow to the engine, leading to a lean fuel mixture and potentially triggering code P1171.

5. Is it safe to continue driving with OBDII code P1171 present?

- It is not recommended to ignore OBDII code P1171, as a lean fuel mixture can cause engine damage over time and may lead to more serious issues if left unresolved.

6. How can I reset OBDII code P1171 after making necessary repairs?

- Once you have addressed the underlying issue causing the lean fuel mixture, you can reset the code using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes.

7. Can a faulty fuel pump cause OBDII code P1171?

- Yes, a failing fuel pump can result in inadequate fuel delivery to the engine, causing a lean fuel mixture and potentially triggering code P1171.

8. Are there any maintenance tips to prevent OBDII code P1171 from recurring?

- Regularly inspecting and replacing the air filter, fuel filter, oxygen sensor, and performing routine fuel system maintenance can help prevent the recurrence of code P1171.

9. Will driving at high altitudes affect OBDII code P1171?

- Driving at high altitudes can sometimes lead to a lean fuel mixture due to lower oxygen levels. However, if the code persists, it is best to investigate other potential causes.

10. Can a misfiring spark plug cause OBDII code P1171?

- Yes, a misfiring spark plug can contribute to a lean fuel mixture and trigger code P1171. It is essential to address any misfire issues promptly to prevent further complications.