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2003 Nissan Pathfinder P0171 Code: System Too Lean (Bank 1) - Diagnosis and Fixes

Model: 2003 Nissan Pathfinder Fault Code: P0171 Posted: 2015-12-21 09:59

Hi everyone, I'm experiencing a P0171 diagnostic trouble code on my 2003 Nissan Pathfinder with an automatic transmission. The code indicates 'System Too Lean (Bank 1)', meaning the air-fuel mixture in the engine is too lean—there's excessive air and insufficient fuel. Can anyone explain what this means and provide practical steps to resolve it? I've used a OBD2 scanner to confirm the issue, and I'd like to know if there are common causes or solutions for this code on my vehicle model.

Related fault codes
P0171
Comments (2)
Anonymous 2015-12-21 10:07

Hi! This is a 2003 Nissan Pathfinder with an automatic transmission. The OBD2 scan shows P0171 — System Too Lean (Bank 1). Could someone explain what this code means and what steps I should take to fix it? Thanks for any advice.

Anonymous 2015-12-21 10:21

P0170/P0171 on a 3.5L engine typically refers to Bank 1, which is the side of the engine with cylinder #1. The air-fuel mixture is too lean—too much air and not enough fuel in the exhaust stream. Common causes include vacuum leaks or a partially clogged fuel injector. I recommend starting with cleaning the Mass Airflow Sensor (MAF), checking for vacuum leaks, and adding a fuel treatment like Techron or Seafoam. After these steps, re-scan to see if the code clears. Let me know how it goes!