Tank Leak Diagnosis System, Vehicles From My 2013

• The function of the leak detection system is based on the premise that the fuel systems creates a natural vacuum when the fuel in the fuel tank -6- becomes colder.
• The Fuel Tank Leak Detection Control Module -J909- -3- with integrated Fuel Tank Pressure Sensor -G400- monitors the vacuum and the temperature inside the fuel tank. The system is considered to be closed if the measured vacuum is 2.5 mbar.
  Fig 1: Tank Leak Diagnosis System (From MY 2013)

  Courtesy of AUDI OF AMERICA, LLC
• There is a leak in the fuel system if there is not vacuum, which will result as an entry in the control module Diagnostic Trouble Code (DTC) memory.

1 -Breather Line

2 - EVAP Canister

4 - Bleed Line to the Engine

5 - Signal Wire to the Engine Control Module -J623-

7 - Not installed