Fuel Tank Ventilation System - Above Limit

P0441

Fuel Tank Ventilation System - Above Limit

Function
Fuel tank ventilation diagnosis is employed for detecting leaks in the fuel tank ventilation system. In this process, a pressure test is performed at idle speed and with the vehicle stationary.
The EVAP canister purge valve is opened and the shutoff valve closed. This causes a vacuum to build up in the tank, which is measured by the pressure sensor.
At a particular vacuum, the EVAP canister purge valve is closed. The system is now sealed. The time it takes for the vacuum to disappear establishes whether or not there are leaks in the system.

Diagnosis conditions
- Oxygen sensing system active
- No secondary air
- No secondary air diagnosis
- Air mass [<] 30 kg/h
- Engine running
- Vehicle speed = 0 km/h
- Intake air temperature between -12 °C and 60 °C
- Battery voltage [>] 11 V
- Engine load [<] 2.4 ms
- The vehicle must not be at an altitude of above 2448 m
- Time elapsed after engine start-up [>] 990 sec.
- No faults in: Throttle position sensor, idle air control, load sensing, misfire detection, vehicle speed, EVAP canister purge valve, idle air control valve, mass air flow sensor, voltage supply, pressure sensor, shutoff valve and engine temperature

P0441:

NOTE: Fuel tank ventilation can be activated with the Porsche System Tester 2 in the Short test menu.

System Overview







Diagnosis Procedure







1 Check tightness of EVAP canister purge valve.

1. Remove front right-hand wheel housing liner.

NOTE: Before detaching the ventilation lines from the EVAP canister, clean the area around the connections. Dirt must not be allowed to get into the connectors.

2. Detach the ventilation line to the EVAP canister purge valve from the EVAP canister (protective cap).







3. With special tool 9160/1, generate a vacuum of 200 mbar (0.2 bar).

If no vacuum can be built up, replace the EVAP canister purge valve.