P0171 Code Explained: Causes, Diagnosis & Fix for Vacuum Leak / System Too Lean Bank 1

Dealing with a P0171 code? This common engine code means your system is running too lean on bank 1 — usually caused by a vacuum leak, faulty oxygen sensor, or mass airflow issues. In this short video, we’ll explain the causes of P0171, how to spot a vacuum leak, and the best way to diagnose and fix P0171 using tools like a smoke machine. Learn how to recognize the symptoms, understand the P0171 error code, and perform a proper diagnosis of P0171. If you’ve ever searched how to fix P0171 or wondered what DTC P0171 means, this guide will help you find the problem and fix it fast. 👉 Subscribe for more quick diagnostics and car repair tips. #p0171 #vacuumleak #carrepair