Volvo Penta D13 Operator's Manual page 25

Presentation
Shut-down
Should any solution remain in the hoses in freezing
weather, the entire system can be damaged. To avoid
this and any solution spillage, the system is equipped
with automatic drainage when the engine is switched
off so that hoses, the pump and injector are emptied
and the solution runs back to the tank.
If the tank is frozen it will take 24 hours until it is
emission compliant.
NOTICE! The automatic drainage only works when the
engine is stopped using the ignition switch or the stop
button on the instrument panel (depending on
application), not if only the engine power supply is
disconnected. If the system is not drained properly,
solution may squirt out if the hoses are disconnected.
CAUTION!
Wait at least two minutes after the engine has been
turned off before removing the AUS/DEF hoses so that
automatic drainage and depressurization of the AUS
dosing system is completed.
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