P0446

P0446

EVAP Canister Shutoff Valve (Function) - Below Limit

Diagnosis conditions
- Oxygen sensing system active
- No secondary air diagnosis
- Engine running
- Vehicle speed = 0 km/h
- Intake air temperature between 5 °C and 50 °C
- Engine starting temperature between 5 °C and 55 °C
- Battery positive voltage greater than 11 V
- Engine load less than 30%
- EVAP canister burden less than 3
- Altitude correction factor greater than 0.75
- Time elapsed after engine start-up [>] 990 seconds (16.5 minutes) or mixture adaptation completed
- No fault for throttle position sensor, idle air control, vehicle speed, EVAP canister purge valve, mass airflow sensor, voltage supply, pressure sensor, shutoff valve or engine temperature in memory

NOTE: Fuel tank ventilation diagnosis is initiated with the Porsche System Tester 2 in the "Short test" menu. This reduces the time elapsed after engine start-up to 30 seconds.

Possible fault cause
- Purge air line blocked
- EVAP canister purge valve sticks in the opened position (this causes continuous vacuum to go from the intake manifold to the tank system)
- EVAP canister shutoff valve is blocked/sticks in the opened position
- Flow resistance of EVAP canister too high (filter deformed/ blocked)
- Pressure sensor connected incorrectly (polarity reversal)

Diagnosis/troubleshooting

NOTE: The EVAP canister purge valve is very sensitive to contamination. If the lines to the EVAP canister have to be detached, the outside of the canister must be cleaned beforehand.

Part 1:

Figure: Connecting special tool 9160/1

Part 2: