P0171 on SUBARU WRX — System Too Lean Bank 1

Q: "What does P0171 mean on a SUBARU WRX?"

"P0171 indicates: System Too Lean Bank 1. This is a fuel and air metering code. 2 SUBARU WRX owners have reported this to NHTSA."

Q: "What are the most common causes of P0171 on SUBARU WRX?"

"Based on 2 NHTSA reports, the most commonly cited components are: Fuel/Propulsion System, Engine. These percentages are based on the component field in owner complaints."

Q: "Is P0171 serious on my SUBARU WRX?"

"Of 2 NHTSA reports for this code on SUBARU WRX, none involved a crash or fire. However, any diagnostic code should be evaluated by a qualified mechanic."

Q: "What should I do if my SUBARU WRX shows P0171?"

"1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare."

What P0171 Means on Your SUBARU WRX

P0171 is a diagnostic trouble code indicating: System Too Lean Bank 1. This code relates to the fuel and air metering system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

2 SUBARU WRX owners have reported this issue to NHTSA across model years 2008-2019. Most reports come from the 2008, 2019 model years. The most commonly reported component is Fuel/Propulsion System (50.0% of reports).

Real SUBARU WRX Owner Reports

Source: NHTSA Complaints Database

"For the last month or so i had smelled gas fumes periodically when the my car was idling. a few days ago the car went into limp mode. i had the ecu code read at a local store and the technician there stated that the engine code was "p0171 system too lean (bank 1)"."

— 2008 SUBARU WRX owner · FUEL/PROPULSION SYSTEM · Filed 02/02/2013

"At 77,000 miles, my vehicle suffered a major failure where the #2 connecting rod and piston were destroyed, requiring a short block replacement. This repair was performed by Autonation West Subaru in Golden, Colorado and was covered under the SAS gold plan, certified pre-owned 7yr/100,00mi."

— 2019 SUBARU WRX owner · ENGINE · Filed 09/07/2025

All reports filed by vehicle owners directly with the U.S. Department of Transportation.

📊 Complaint Trend by Model Year

1

'08

1

'19

Common Causes on SUBARU WRX

Based on NHTSA complaint component analysis for this vehicle.

FUEL/PROPULSION SYSTEM 50%

ENGINE 50%

What To Do Next

1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.

Frequently Asked Questions

What does P0171 mean on a SUBARU WRX? ▾

P0171 indicates: System Too Lean Bank 1. This is a fuel and air metering code. 2 SUBARU WRX owners have reported this to NHTSA.

What are the most common causes of P0171 on SUBARU WRX? ▾

Based on 2 NHTSA reports, the most commonly cited components are: Fuel/Propulsion System, Engine. These percentages are based on the component field in owner complaints.

Is P0171 serious on my SUBARU WRX? ▾

Of 2 NHTSA reports for this code on SUBARU WRX, none involved a crash or fire. However, any diagnostic code should be evaluated by a qualified mechanic.

What should I do if my SUBARU WRX shows P0171? ▾

1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare.