⚡ AUTO CODE FIX
🔍
Fuel SystemModerate✅ DIY Friendly

P0171

System Too Lean Bank 1

The engine is running too lean on Bank 1. The ECM is adding fuel to compensate but cannot get rich enough.

SeverityModerate
CategoryFuel System
Est. Repair Cost$50–$500
Code TypePowertrain
DIY RepairYes

⚡ Common Causes

⚠️ Symptoms

✅ How to Fix — Step by Step

  • Step 1:Smoke test entire intake for vacuum leaks
  • Step 2:Clean MAF sensor
  • Step 3:Check fuel pressure
  • Step 4:Clean or replace fuel injectors
  • Step 5:Replace O2 sensor if readings are erratic
💡 Pro Tip: P0171 is one of the most common codes — a cracked intake hose or loose PCV hose is the culprit 50% of the time.

Repair Cost Estimate

Full Repair Estimate
$50–$500
DIY Possible?
YES
Severity
Moderate

Frequently Asked Questions

What does OBD2 code P0171 mean?+
P0171 stands for System Too Lean Bank 1. The engine is running too lean on Bank 1. The ECM is adding fuel to compensate but cannot get rich enough.
What causes code P0171?+
Vacuum leak (most common); Dirty or failing MAF sensor; Weak fuel pump; Clogged fuel injectors; Faulty upstream O2 sensor
How do I fix code P0171?+
Smoke test entire intake for vacuum leaks; Clean MAF sensor; Check fuel pressure; Clean or replace fuel injectors; Replace O2 sensor if readings are erratic
How much does it cost to fix P0171?+
Estimated repair cost for P0171 is $50–$500.
Is P0171 DIY-friendly?+
Yes — P0171 is generally DIY-friendly with basic tools.

AI Diagnosis

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