LINK AS 1394868 - Caterpillar

Flushing Procedure
Turn the key switch to the OFF position. The key switch must be OFF to allow the Diesel Exhaust Fluid (DEF) pump to purge, ensuring the system is free of pressurized DEF.Note: In certain circumstances, allow for a maximum of 15 minutes after turning the key switch to the OFF position before turning the battery disconnect switch to the OFF position. Refer to Operation and Maintenance Manual, "Battery Disconnect Switch" for more information.
Position the suitable container under the DEF tank , drain the existing DEF from the tank.Note: All DEF/ Distilled water drained or flushed during this procedure must be disposed of as per local regulations and mandates.
Illustration 1 g03710738
Typical example
(8) DEF pump
(9) DEF filter cap
Replace the DEF filter. Refer to Operation and Maintenance Manual, "Diesel Exhaust Fluid Filter - Clean/Replace" for the correct procedure.Note: This filter is to be used for the flushing process only.
Refill the DEF tank to the maximum level with distilled water
Start the engine. Refer to Operation and Maintenance Manual for the correct procedure. Run at low idle for 30 minutes to circulate the fluid.
Turn the key switch to the OFF position. The key switch must be OFF to allow the DEF pump to purge, ensuring the system is free of pressurized distilled water.Note: In certain circumstances, allow for a maximum of 15 minutes after turning the key switch to the OFF position before turning the battery disconnect switch to the OFF position. Refer to Operation and Maintenance Manual, "Battery Disconnect Switch" for more information.
Position the suitable container under the DEF tank, drain the distilled water from the tank.
Replace the DEF filter. Refer to Operation and Maintenance Manual, "Diesel Exhaust Fluid Filter - Clean/Replace" for the correct procedure.
Fill the DEF tank to the appropriate level with new DEF. Operation and Maintenance Manual, "Diesel Exhaust Fluid - Fill" for more information. The new DEF must meet ISO 22241 standards.
Start the engine refer to Operation and Maintenance Manual for the correct procedure. Connect to the electronic service tool,
Perform the "Aftertreatment System Functional Test" in the electronic service tool. Refer to Troubleshooting Guide, Service Tool Features. This test will verify that the DEF system is working correctly following the flush and filter replacement.