Tag: audi a4 air box mod

Diagnosing a 2008 Audi A4 with fault code P1111. After removing the air filter it was evident why the car had the persistent P1111 Oxygen sensor control; Bank 1: System too lean. It is important to keep in mind when modifying cars that you know how to properly service them after you have modified them, this is a great example of neglecting service after modifying a car. Other things to look at when fixing a car with fault code P1111; Check Mass Air Flow Sensors Check Intake Air System Leaks Check Fuel Injectors Check Exhaust System for Leaks Check Fuel Delivery Filter