4377650 | Genuine Cummins® DEF Doser Injector SCR 2.2 For EPA17 6.7 L ISB/QSB

1. Reduces harmful NOx emissions

• Sprays DEF into hot exhaust gases

• DEF breaks down into ammonia

• Ammonia reacts in the SCR catalyst

• Converts NOx into nitrogen and water

Why it matters:
NOx emissions are harmful and tightly regulated by EPA standards.

2. Enables SCR system operation

• Acts as the delivery point for DEF in the SCR system

• Works with the DEF pump, sensors, and ECM

Why it matters:
Without proper dosing, the SCR system cannot function.

3. Prevents engine derate and shutdown

• Ensures emissions stay within limits

• Avoids warning countdowns and reduced power modes

Why it matters:
Keeps the truck running at full power and avoids downtime.

4. Improves emissions efficiency

• Injects precise amounts of DEF based on engine load

• Prevents over-dosing or under-dosing

Why it matters:
Proper dosing protects the SCR catalyst and optimizes DEF consumption.

5. Maintains legal and environmental compliance

• Required for EPA and emissions compliance

• Essential for passing inspections

Why it matters:
Operating without it can lead to fines and out-of-service violations.

6. Protects exhaust components

• Correct spray pattern prevents DEF crystallization

• Reduces buildup and clogging in exhaust

Why it matters:
Extends life of the SCR catalyst and exhaust system.

1. SCR / DEF fault codes

• Check Engine Light on

• SCR efficiency or NOx conversion codes
  Why: DEF isn’t being injected correctly (too much, too little, or not at all).

2. Engine derate or speed limitation

• Power reduced

• Countdown to shutdown
  Why: Emissions system can’t meet EPA limits.

3. White crystals or buildup at exhaust

• Chalky white residue near injector or pipe
  Why: DEF leaking, dripping, or poor spray pattern causing crystallization.

4. Excessive DEF consumption

• DEF level drops faster than normal
  Why: Injector stuck open or over-dosing.

5. Strong ammonia or sharp exhaust smell

• Noticeable DEF/ammonia odor
  Why: Over-injection or incomplete SCR reaction.

6. Poor NOx efficiency readings

• NOx sensor codes upstream/downstream
  Why: DEF not atomizing or mixing properly.

7. Injector not clicking or responding

• No audible click during test
  Why: Electrical failure or stuck injector.

8. Clogged or sticking injector

• Intermittent faults

• Works after regen or long drive, then fails again
  Why: DEF crystallization inside injector tip.

9. Rough exhaust flow or visible vapor

• White vapor from exhaust (not smoke)
  Why: Unburned DEF entering exhaust.

10. Won’t pass emissions inspection

• High NOx readings
  Why: DEF not being delivered correctly.