EVAP System Function Test
WARNING: This page is about a different car, the 2024 Audi SQ7, 2024 Audi Q7, 2023 Audi SQ7, and 2023 Audi Q7. However, it is still accessible from the selected car via links, so may be relevant.
Vehicles with High-Voltage System
- In electric driving mode, the Tank Switch-Off Valve -N288- -item 2- closes the breather line -4- to the EVAP canister -3-, so that it is not overfilled with fuel vapor, for example, when driving electrically for days on end.
- Because the pressure in the fuel tank -1- increases due to temperature effects when the breather line is closed, the Fuel Tank Pressure and Temperature Sensor -GX49- -item 5- monitors the tank internal pressure and via the engine control module causes the Tank Switch-Off Valve -N288- to open at a residual pressure of 0.3 bar (4.35 psi). The valve also opens when the fuel filler cap release button is pressed, so that no fuel can squirt out of the filler neck when opening the fuel filler cap to fuel.