HOSE AS 3217144 - Caterpillar

Stopping the engine immediately after it has been working under load can result in overheating and accelerated wear of the engine components.
Before stopping the engine, allow the engine to run at low idle with no load for 5 minutes. This procedure allows the hot areas of the engine to cool gradually and will extend the life of the engine.
Turn the engine start switch to the OFF position. Remove the key.
Be sure that all of the controls are in the OFF position. Be sure that all of the controls are in the proper position for parking the machine. Cooling and Purging of the DEF Lines
After key-off, the DEF pump will circulate the DEF fluid for a given time, in order to cool the DEF injector. Also, the DEF pump will purge the DEF system of fluid to protect the system from freeze of the DEF fluid in cold conditions.With the DOC and SCR aftertreatment system the cooling and purging will take a minimum of 3 minutes and a maximum of 10 minutes. The time taken will depend on the temperature with the aftertreatment system.When the DOC, DPF and SCR system is operating with exhaust gas temperatures below 425° C (797° F) before key-off, the cooling and purging will also take 6 minutes. When the DOC, DPF, and SCR aftertreatment system operates at temperatures above 425° C (797° F), and key-off occurs the cooling and purging will take a maximum of 15 minutes.For example, the maximum cool-down and purge time is only likely to be encountered in a certain combination. Full-load rated speed operation and the DPF in a regeneration mode occurring simultaneously, immediately before key-off.