A062H259 | Genuine Cummins® Diesel Exhaust Fluid Header

DEF Return Fitting Dia. (IN): 3/8 SAE J2044
Coolant Outlet Fitting Dia. (IN): 5/8 Hose Bead
Tank Interface: 4.05 Dia. Bore Seal
Electrical Connector: Deutsch DT4 (STD)
Sensor Type: Digital (canbus)
DEF Suction Fitting Dia. (IN): 3/8 SAE J2044
Coolant Inlet Fitting Dia. (IN): 5/8 Hose Bead
In-Tank Filter: 40µ

•  Trucks & Buses: Lion Bus, Spartan Motors, Eldorado, E-ONE, Freightliner, Kenworth, Peterbilt, International, Volvo, Western Star.

• Heavy Equipment & Off-Highway: Doosan Bobcat, SANY, GREMO AB, MI-JACK PRODUCTS INC., Wausau Equipment, CMI (Construction Machinery Inc.).

• Engine Architecture: Fits Cummins® engines (ISX15, X15, ISL9, L9, ISB6.7, B6.7) equipped with SCR / DEF emissions control systems.

• Tank Depth: Designed for DEF tanks requiring a 22-inch sensor header configuration.

1. What is it?

The assembly combines multiple monitoring and fluid-delivery functions into a single 22-inch drop-in tank module. It allows the vehicle's Engine Control Module (ECM) to monitor DEF levels and quality, ensuring full compliance with Selective Catalytic Reduction (SCR) emission regulations.

2. Core Functions

• Fluid Level Sensing: Continuously measures the remaining DEF volume to alert the driver when a refill is required.

• Fluid Quality & Concentration Sensing: Monitors the chemical concentration of the urea solution to ensure it meets the standard ~32.5% purity level.

• Temperature Monitoring & Heating: Tracks DEF fluid temperature and utilizes an integrated coolant-heated loop to thaw frozen DEF in cold climates.

• Suction & Return Lines: Houses the internal tubes that draw DEF to the dosing unit and return uninjectable fluid back to the tank.

• Dash displays “Poor DEF Quality”, “Check DEF System”, or “SCR Fault”

• Even when you are using fresh, high-quality DEF
  This happens when the quality sensor inside the head fails.

2. Incorrect DEF Level Reading

• DEF gauge stuck on empty, full, or bouncing

• Sudden drop to empty even with DEF in the tank
  This means the level sensor is malfunctioning.

3. Engine Derate / Loss of Power

A bad DEF head can trigger:

• 25% – 40% power derate

• Speed limit (5 mph limp mode on some models)
  The engine does this to protect emissions compliance.

4. DEF Temperature Sensor Fault

• Code for DEF temperature high or low

• DEF heater not turning on or staying on too long
  Bad temperature data causes ECM confusion.

5. SCR / NOx System Warning Lights

Common dash messages:

• “Service Emissions System”

• “SCR Fault”

• “Aftertreatment System Problem”

The DEF head feeds critical data to these systems.

6. No DEF Suction or DEF Pump Not Working

If the pickup tube, filter, or internal electronics fail:

• DEF pump may run dry

• System won’t prime

• No DEF injection occurs

7. Trouble Codes Stored in ECM

You may see codes related to:

• DEF quality

• DEF temperature

• DEF level

• DEF tank heater circuit

• DEF pressure or delivery

These commonly point directly to the DEF head.

8. Crystallization Around DEF Tank or Connectors

• White crystals forming around the DEF head

• Indicates leaks or internal cracking
  Crystallized DEF often damages wiring or sensors.

9. DEF Freezes or Doesn’t Thaw Properly

If the heater inside the head fails:

• DEF remains frozen

• No dosing occurs

• Cold-weather SCR faults appear