Fuel System, Checking For Leaks
WARNING: This page is about a different car, the 2016 Audi A3 and 2015 Audi A3. However, it is still accessible from the selected car via links, so may be relevant.
- The function of the leak detection system is based on the premise that the fuel system creates a natural vacuum when the fuel in the fuel tank becomes colder.
- The Fuel Tank Pressure Sensor -G400- -3- senses the vacuum in the vent line -4- near the EVAP canister -1-. The Fuel Tank Leak Detection Control Module -J909- -7- is attached directly to the wall of the fuel tank -6- and monitors the temperature inside the fuel tank. The system is considered to be sealed if the measured vacuum is 2.5 mbar. If there is no vacuum, then there is a leak in the fuel system, which will result in an entry in the engine control module DTC memory.
2 - Signal Wire to Engine Control Module -J623-
5 - Bleeder Line to Engine