5418511 | Genuine Cummins® Inlet Catalyst Module 6.7L ISB/QSB

1. Reduce Harmful Exhaust Gases

It converts:

• Carbon monoxide (CO) → Carbon dioxide (CO₂)

• Unburned hydrocarbons (HC) → CO₂ and water

This reduces toxic emissions before they reach the tailpipe.

2. Generate Heat for DPF Regeneration

During active regeneration:

• Extra fuel is introduced into the exhaust.

• The inlet catalyst oxidizes that fuel.

• This creates high temperatures needed to burn soot in the Diesel Particulate Filter (DPF).

Without it, proper regeneration would not happen.

3. Prepare Exhaust for Downstream Components

It conditions exhaust gases before they enter:

• The DPF

• The SCR (Selective Catalytic Reduction) system

This improves overall emissions efficiency.

4. Support Emissions Compliance

Modern diesel engines must meet strict EPA and global standards.
The inlet catalyst module helps the vehicle stay legally compliant.

1. Check Engine Light

• Engine light turns on

• Fault codes related to:

  • Catalyst efficiency below threshold

  • Aftertreatment fuel system faults

  • DOC temperature performance issues

2. Frequent or Failed DPF Regeneration

Since the inlet catalyst helps create heat for regeneration:

• DPF regen cycles happen too often

• Regeneration fails

• DPF becomes clogged faster than normal

This is one of the biggest signs.

3. Reduced Engine Power (Limp Mode)

If the DOC is restricted or not functioning properly:

• Exhaust backpressure increases

• Engine may limit power

• Vehicle may enter limp mode

4. Excessive Exhaust Smoke

• Black smoke during acceleration

• Strong diesel smell

• Unburned fuel smell during regeneration

This can indicate poor oxidation of hydrocarbons.

5. Poor Fuel Economy

If regeneration events are frequent or inefficient:

• Extra fuel is used

• MPG drops noticeably

6. Overheating or Excessive Exhaust Temperatures

• Abnormally high exhaust temps

• Risk of damage to DPF or downstream SCR components

7. Rattling Noise from Exhaust

If the catalyst substrate inside breaks:

• You may hear rattling from the exhaust housing