Cummins ISX11.9 CM2250 – Service Manual 011-060   Aftertreatment Diesel Exhaust Fluid Dosing Unit Filter

The diesel exhaust fluid (DEF) dosing unit filter is a 10-micron filter designed to prevent foreign objects that may be suspended in the DEF from entering the dosing system. Debris can cause permanent damage and premature malfunctions to either the aftertreatment DEF dosing unit or the aftertreatment DEF dosing valve. The aftertreatment DEF dosing unit filter is a maintenance item.

Use the following procedure for information on handling incorrect or contaminated DEF. Refer to Procedure 011-056 in Section 11.

The aftertreatment DEF dosing unit consists of the following components:

1. Aftertreatment DEF dosing unit filter cap
2. Aftertreatment DEF dosing unit filter equalizing element
3. Aftertreatment DEF dosing unit filter element.

Locate the aftertreatment DEF dosing unit on the vehicle. Notice the dome shape filter cap.

Visually inspect around the seal and vent of the aftertreatment DEF dosing unit filter cap for signs of leakage.

DEF leaks leave a white deposit. If deposits are found, see the Clean and Inspect for Reuse section of this procedure.

WARNING  Diesel exhaust fluid (DEF) contains urea.  Do not get the substance in your eyes. In case of contact, immediately flush eyes with large amounts of water for a minimum of 15 minutes. Do not swallow. In the event the diesel exhaust fluid is ingested, contact a physician immediately. Reference the Materials Safety Data Sheet (MSDS) for additional information.

WARNING  Batteries can emit explosive gases. To reduce the possibilityof personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.

WARNING  The diesel exhaust fluid line connecting the aftertreatment diesel exhaust fluid dosing unit to the aftertreatment diesel exhaust fluid dosing valve is under low pressure and should not be disconnected while the engine is running or before the system has completed the purge process after engine shutdown.  Disconnecting the diesel exhaust fluid line while under low pressure could cause diesel exhaust fluid to spray.

NOTE: Do not disconnect the vehicle batteries until the DEF dosing system has completed the purge cycle.  Before beginning to remove and/or disconnect any components, wait at least 5 minutes after the keyswitch is turned OFF for the aftertreatment DEF dosing system to purge the DEF from the system.  The purge cycle is an automatic process and does not require intervention to occur.  The aftertreatment DEF dosing unit will create an audible pumping noise during the purging process.

• Disconnect the batteries. Refer to the OEM service manual.

NOTE: Do not power wash or steam clean this unit. Use compressed air to remove any loose debris.

There may be residual DEF in the filter housing. A collection container placed below the DEF filter cap is recommended. 

Unscrew the DEF filter cap (1).

Remove the aftertreatment DEF filter equalizing element (2).

Remove the old aftertreatment DEF dosing unit filter element (3).

NOTE: If the aftertreatment DEF dosing unit filter is being removed as part of a maintenance interval, discard the equalizer element and filter.

If it is suspected that contaminated DEF has gone through the DEF dosing system, check the DEF filter prior to discarding the filter.

Inspect the DEF filter for evidence of contaminated DEF.  Use visual and aroma characteristics of the filter to determine if contaminated fluid has passed through the dosing system. 

Use the following procedure for further information on contaminated DEF. Refer to Procedure 011-056 in Section 11.

Inspect the DEF filter for debris.  If debris is evident, also inspect the following:

• The DEF tank pickup screen. Refer to the OEM service manual.
• The aftertreatment DEF dosing unit inlet connector. Refer to Procedure 011-058 in Section 11.

Discard the filter element and equalizing element.

Inspect the aftertreatment DEF dosing unit filter cap for cracks or holes that could create a DEF leak path.

Inspect the condition of the threads on the aftertreatment DEF dosing unit cap. If the threads are damaged, replace the aftertreatment DEF dosing unit filter cap.

Inspect the aftertreatment DEF dosing unit threads. This is especially important if the aftertreatment DEF dosing unit cap was damaged.

If the aftertreatment DEF dosing unit threads are damaged, replace the entire aftertreatment DEF dosing unit.

Clean the aftertreatment DEF dosing unit cap with warm water and a clean cloth.

NOTE: Never operate the vehicle with the DEF cap removed.

NOTE: Lubrication of the DEF filter o-rings is not required.

1. Slide the DEF filter equalizing element into the DEF filter cartridge.
2. Insert the assembly into the aftertreatement DEF dosing unit.
3. Install and tighten the cap.

WARNING  Batteries can emit explosive gases. To reduce the possibilityof personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.

CAUTION  Do not use the flow test portion of INSITE™ electronic service tool Diesel Exhaust Fluid Doser Pump Override Test to check the system for leaks.  This will spray DEF into the exhaust system at too low of a temperature to evaporate, resulting in deposit formations in the exhaust system.

• Connect the batteries. Refer to the OEM service manual.

NOTE: The aftertreatment DEF dosing system will not prime until the correct SCR temperatures are reached. To verify that there are not any DEF leaks, test drive the vehicle for a minimum of 15 minutes to get the SCR system up to temperature.

• Start the vehicle and check for leaks.