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P0171 on Ford F-150

System Too Lean Bank 1

NHTSA Reports

Severity

medium

Most Affected

2005, 2006

Crashes / Fires

0 / 0

Source: NHTSA Complaints Database · SAE J2012

Last reviewed: Aug 7, 2026 Last updated: Aug 7, 2026

Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Ford F-150 context without treating complaints as confirmed diagnoses.

Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).

SAE J2012 Diagnostic Trouble Code Definitions — Generic diagnostic trouble code definition reference for P0171.
NHTSA recalls, complaints, and manufacturer communications — Used to check public owner complaint context, recall status, and safety-related manufacturer communications by VIN or vehicle.

Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.

What P0171 Means on Your Ford F-150

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 FORD F-150 owners have reported this issue to NHTSA across model years 2005-2006. Most reports come from the 2005, 2006 model years. The most commonly reported component is Engine And Engine Cooling (50.0% of reports).

Real Ford F-150 Owner Reports

Source: NHTSA Complaints Database

"Experienced sudden loss of power steering and power brakes while normal and routine driving on highway. no warning of any kind that failure was about to occur. engine ran rough, engine light warning came on after brake and steering failure and then engine shut off."

— 2005 Ford F-150 owner · ENGINE AND ENGINE COOLING · Filed 2007-08-04

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

📊 Complaint Trend by Model Year

'05

'06

Common Causes on Ford F-150

Based on NHTSA complaint component analysis for this vehicle.

ENGINE and ENGINE COOLING 50%

ELECTRICAL SYSTEM,ENGINE,FUEL/PROPULSION SYSTEM 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.