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P0440
P0440
Diagnosis information - DME V6 DFI Tank ventilation system
NOTE: The tank valve is located on the left in the direction of travel beside the throttle adjusting unit.
NOTE: In the case of the Turbo, the tank vent line feeds into both the connection piece of the positive crankcase ventilation as well as into a hose which is routed to the intake side of the turbocharger.
NOTE: The diagnosis is carried out on the tank vent by evaluating the oxygen sensor (or the throttle adjusting unit or the retraction of the ignition timing angle) as a result of rich/lean fluctuations (or changes in speed) when opening or closing the tank valve.
Diagnostic conditions
- Battery positive voltage between 10 V and 16 V
- Time after engine start greater than 10 minutes
- Idle speed
- Engine temperature > 90 °C (194 °F)
- All oxygen sensors ready for operation
- No oxygen sensor fault stored
- No tank vent driver fault stored
Possible fault causes
- Tank vent faulty (remains stuck in an open or closed position)
- Tank vent installed back to front
- Leak in scavenging lines between tank vent and positive crankcase ventilation (in the Turbo via a T-piece also on the intake side of the turbocharger)
- Scavenging lines between tank vent and positive crankcase ventilation trapped or blocked (in the Turbo via a T-piece also on the intake side of the turbocharger)