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P0171 Code — Meaning, Real Fixes & Costs | MyCarFault
P0171
🟡 Medium Engine system

P0171 — System Too Lean Bank 1

12 Driver reports
12 Solved cases
6 Verified fixes
0 Wrong repairs reported

📊 Diagnostic Overview

Severity, cost and difficulty for P0171, based on data already on this page.

Severity
🟡 Medium
Diagnostic Difficulty
Moderate
System
Engine
Common Causes (based on confirmed repairs)
  • Most common causes in order: 1) Vacuum leak — spray carb cleaner near intake joints, listen for RPM change. 2) Dirty MAF sensor — clean with MAF cleaner spray ($10), often fixes it immediately. 3) Weak fuel pump — check fuel pressure. 4) Stuck PCV valve. 1 vehicle
  • Cleaned MAF sensor with dedicated MAF cleaner spray. Also found small cracked vacuum hose near intake manifold. Replaced hose $8. P0171 cleared and has not returned. 218 vehicles
  • Aftermarket intake changed airflow characteristics confusing the MAF sensor calibration. Options: 1) Return to stock intake. 2) Get ECU tune to recalibrate for new intake. 3) Use a short ram intake instead of full CAI which places MAF in less turbulent ai 1 vehicle
  • Cleaned MAF sensor with dedicated MAF cleaner spray. Code cleared and has not returned in 10000 miles. 1 vehicle
  • Found large vacuum hose cracked near intake manifold. $8 hose from dealer. Code gone immediately. 1 vehicle

📐 Diagnostic Difficulty reflects how many different repairs drivers have tried for P0171 and how often those attempts turned out to be the wrong fix — it is calculated from MyCarFault's own reports, not an official manufacturer rating.

⭐ MOST VERIFIED FIX FOR P0171
Most common causes in order: 1) Vacuum leak — spray carb cleaner near intake joints, listen for RPM change. 2) Dirty MAF sensor — clean with MAF cleaner spray ($10), often fixes it immediately. 3) Weak fuel pump — check fuel pressure. 4) Stuck PCV valve.
Worked in 0% of voted outcomes · Verified by 0 drivers
⚪ Unverified

Most Verified Fixes for P0171

Ranked by confidence score — same vehicle matches weighted higher.

Most common causes in order: 1) Vacuum leak — spray carb cleaner near intake joints, listen for RPM change. 2) Dirty MAF sensor — clean with MAF cleaner spray ($10), often fixes it immediately. 3) Weak fuel pump — check fuel pressure. 4) Stuck PCV valve. 0%
0 worked · 1 total votes · ⚪ Unverified
Cleaned MAF sensor with dedicated MAF cleaner spray. Also found small cracked vacuum hose near intake manifold. Replaced hose $8. P0171 cleared and has not returned. 218 cases
No repair votes yet · 218 vehicles · ⚪ Unverified
Aftermarket intake changed airflow characteristics confusing the MAF sensor calibration. Options: 1) Return to stock intake. 2) Get ECU tune to recalibrate for new intake. 3) Use a short ram intake instead of full CAI which places MAF in less turbulent ai 1 case
No repair votes yet · ⚪ Unverified
Cleaned MAF sensor with dedicated MAF cleaner spray. Code cleared and has not returned in 10000 miles. 1 case
No repair votes yet · ⚪ Unverified
Found large vacuum hose cracked near intake manifold. $8 hose from dealer. Code gone immediately. 1 case
No repair votes yet · ⚪ Unverified
Large boost leak found — intercooler hose had split at clamp. Replaced hose and tightened all charge pipe clamps $35. P0171 cleared immediately. 1 case
No repair votes yet · ⚪ Unverified

Driver Reports — P0171 12 reports

🟢 SOLVED 80% Cadillac CT5 2020 Check engine light P0171 lean mixture
2020 👁 2,031
🟢 SOLVED 80% Mercedes-Benz CLA 2017 Check engine light P0171 lean mixture
Mercedes-Benz 2017 👁 2,025
🟢 SOLVED 80% Cadillac XT5 2022 Check engine light P0171 lean mixture
2022 👁 2,020
🟢 SOLVED 80% Honda Odyssey 2017 Check engine light P0171 lean mixture
Honda 2017 👁 2,008
🟢 SOLVED 80% Ford EcoSport 2020 Check engine light P0171 lean mixture
Ford 2020 👁 1,992
🟢 SOLVED 80% Volkswagen Atlas 2017 Check engine light P0171 lean mixture
Volkswagen 2017 👁 1,992
🟢 SOLVED 80% Chevrolet Blazer 2018 Check engine light P0171 lean mixture
2018 👁 1,954
🟢 SOLVED 80% Audi TT 2017 Check engine light P0171 lean mixture
Audi TT 2017 👁 1,941
🟢 SOLVED 80% Lexus UX 2017 Check engine light P0171 lean mixture
2017 👁 1,917
🟢 SOLVED 80% Volkswagen Arteon 2012 Check engine light P0171 lean mixture
Volkswagen 2012 👁 1,904
🟢 SOLVED 80% Audi e-tron 2016 Check engine light P0171 lean mixture
Audi 2016 👁 1,900
🟢 SOLVED 80% Ford F-150 2012 Check engine light P0171 lean mixture
Ford 2012 👁 1,899

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