AutoCodes

OBD-II / P0171

System too lean — bank 1

The control module is adding fuel because it sees too much air or too little fuel on bank 1.

Possible causes

  1. 01Vacuum leak
  2. 02Contaminated or faulty airflow sensor
  3. 03Low fuel pressure
  4. 04Exhaust leak ahead of the sensor

Safe checks

  • Inspect hoses and clamps.
  • Check whether P0174 is also present.
  • Review fuel trims with suitable equipment.

Non sostituisce la diagnosi in officina. Ti aiuta prima a capire e decidere. Original editorial content; always confirm manufacturer procedures and specifications.