P/N: 4067677C1 | Genuine International® DEF Return Tube Skip to content
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4067677C1 | Genuine International® DEF Return Tube
International

4067677C1 | Genuine International® DEF Return Tube

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Order within the next Jun 19 for delivery by Jun 24.
  • Product SKU: 4067677C1
  • Availability: In Stock
$98.00 - $98.00
$98.00
$98.00 - $98.00
$98.00
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Description: DEF Return Tube
Condition: New 
Brand: International®
Part Number: 4067677C1 

Fitment Guide: International


A DEF Return Tube is part of a diesel engine’s SCR (Selective Catalytic Reduction) system. It is a small line that returns unused or excess Diesel Exhaust Fluid (DEF) back to the DEF tank or dosing system.

 

1. Returns unused DEF

  • Not all DEF sent to the injector is used.
  • The return tube carries the extra DEF back instead of wasting it.

2. Maintains correct system pressure

  • Helps regulate pressure in the DEF dosing circuit.
  • Prevents pressure buildup that could damage components.

3. Improves dosing accuracy

  • Keeps flow stable so the system can meter DEF correctly.
  • Supports proper SCR operation and emissions control.

4. Reduces waste and improves efficiency

  • Reuses excess DEF instead of losing it.
  • Helps maintain consistent fluid supply in the system.

5. Helps prevent clogging and crystallization

  • Keeps DEF moving instead of sitting in lines.
  • Reduces the chance of DEF forming crystals inside components.


Signs of Faulty:

 

1. DEF leaks or white crystals

  • Wet spots or dried white crust around the tube or fittings
  • Crystallized DEF buildup (chalky white residue)
  • Often caused by cracks or loose connections

2. SCR or DEF system warning lights

  • Check engine light on
  • “SCR system fault” or “DEF system malfunction” messages
  • Emissions-related trouble codes

3. Pressure or dosing faults

  • Low DEF pressure or unstable pressure readings
  • “DEF dosing performance” or “injection system fault” codes
  • System may struggle to maintain correct flow balance

4. Abnormal DEF usage

  • DEF consumption higher or lower than normal
  • Inconsistent DEF level changes in the tank

5. Poor engine performance (derate)

  • Reduced engine power
  • Speed limitation due to emissions faults
  • Occurs when SCR system cannot operate correctly

6. Pump or injector strain

  • Doser pump running more often than usual
  • Noisy operation or frequent cycling
  • Injector may clog due to improper return flow

7. Crystallization inside the system

  • Blockage forming in return line or nearby fittings
  • DEF backing up and drying inside components
  • Can spread to injector or dosing unit



Navistar International Corporation is an American company specializing in the production of trucks, buses, diesel engines and other transport equipment. They are known for their products for various industries including logistics, construction and public transport. The company is also actively working on the development of electric and hybrid solutions for the transport industry.

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