Fuel Tank Ventilation System (Major Leak) - Below Lower Limit

P0455

Fuel Tank Ventilation System (Major Leak) - Below Lower 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. If no vacuum builds up, a major leak is present. Diagnosis is then terminated.

Diagnosis conditions
- Oxygen sensing system active.
- No secondary air.
- No secondary air diagnosis.
- Air mass [<] 30 kg/h.
- Idle speed.
- 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 [>] 1000 sec.
- No faults: 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.

P0445:

System Overview







Diagnosis Procedure







1 Check tank cap.

1. Check whether the tank cap is present.
2. Check whether the tank cap is correctly screwed on.

2 Check ventilation lines to EVAP canister.







1. Remove front right-hand wheel housing liner.
2. Check whether ventilation lines are attached to the EVAP canister.

3 Check ventilation lines to operating purge valve.







1. Remove front right-hand wheel housing liner.
2. Check whether ventilation lines are attached to the operating purge valve.

4 Check ventilation line to tank.







1. Remove battery.
2. Remove battery cover.
3. Check whether ventilation line is attached to the fuel tank sender unit.

5 Check ventilation line to EVAP canister purge valve.







Check whether ventilation line is attached to the EVAP canister purge valve.

6 Check ventilation lines.

Check whether ventilation lines are:
- cracked
- broken
- interrupted

7 Check EVAP canister purge valve.







1. Remove front right-hand wheel housing liner
2. Clean EVAP canister in the vicinity of the ventilation lines.
3. Detach the ventilation line to the EVAP canister purge valve from the EVAP canister (connection with protective cap).
4. 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.