Title:

DEF Header Replacement

Number:

SB_694

Release Date:

05/21/2024

Revision Number:

Not Applicable

Revision Date:

Not Applicable

Chassis Type:

Custom Chassis

Component Description:

DEF Header

Warranty:

Limited Base or Emissions

Purpose:
To provide accurate, thorough instructions on the replacement of the DEF Header on Custom Chassis vehicles.
Procedure:
NOTE: Depending on the configuration of your vehicle, the location and configuration of your DEF tank
may vary from the example shown.
1. Attach “DO NOT START” tag to truck ignition switch.
2. Turn battery switch OFF (if equipped) or disconnect batteries.
3. Remove fender liner.

Diesel Exhaust Fluid (DEF) may cause irritation on skin or eyes. Wear personal protective equipment
when handling DEF. If DEF comes in contact with skin, wash with cool water and soap. If DEF comes in
contact with eyes, flush with cool water. Seek medical attention if irritation persists.
4. Using a suitable container, drain DEF tank to less than 50% of fill capacity.
5. Disconnect DEF header electrical connector from aftermarket CAN bus harness.
NOTE: Label coolant and DEF lines and connection points prior to removal to ensure proper installation.
6. Remove two coolant lines from DEF header and drain excess into suitable container.
7. Remove two DEF lines from DEF header and drain excess into suitable container.
8. Remove hardware and tank strap from DEF tank.
NOTE: Note position and orientation of DEF tank prior to removal to ensure proper installation.
9. With the aid of an assistant, tip DEF tank towards wheel and remove DEF tank from support bracket.
10. If there is not enough clearance to remove DEF tank between the wheel and body, raise up rear of
vehicle until enough clearance is gained to remove tank.
11. Loosen band clamp and remove DEF header from DEF tank.
IMPORTANT: DO NOT POLLUTE! Dispose of used DEF in an environmentally responsible manner. If
available, take used DEF to a collection center for recycling. If recycling is not available,
inquire as to the correct procedure for disposal.
12. Drain remainder of DEF through the DEF header opening in the top of the tank and into a suitable
container.
13. Flush tank thoroughly with clean water. Tip tank to ensure all sides are washed, then quickly pour the
water out of the opening in the top of the tank before any contaminates can settle.
14. Install new DEF header in DEF tank and secure with band clamp.
NOTE: Note Coolant In, Coolant Out, and DEF Return connection points on new DEF header. These ports
are the same size and can be mixed up if not noted properly.
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SERVICE BULLETIN #694

15. With the aid of an assistant, slide DEF tank between the wheel and body, then position DEF tank on
support bracket as noted prior to removal.
16. Install tank strap on DEF tank with hardware.
17. Lower vehicle (if raised).
NOTE: Install DEF and coolant lines on proper connection points as noted prior to removal.
18.
19.
20.
21.
22.
23.
24.
25.
26.

Install two DEF lines on DEF header.
Install two coolant lines on DEF header.
Connect DEF header electrical connector to aftertreatment CAN bus harness.
Fill DEF tank to 50% of fill capacity with clean DEF.
Turn battery switch ON (if equipped) or connect batteries.
Remove “DO NOT START” tag from truck ignition switch.
Clear codes with Cummins INSITE.
Start truck and idle for at least 1 minute before moving onto the following step.
Monitor for DEF codes:
a. If no codes are present, reinstall fender liner and fill DEF tank to 100% fill capacity with clean
DEF.
b. If codes are present, refer to DEF header bulletin SB_406 Troubleshooting Diesel Exhaust Fluid
(DEF) Quality Codes for resolution or open a technical support incident on Pierceparts.com.

If any additional support is needed, please open a technical support incident on Pierceparts.com.

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