4394369 | Genuine Cummins® Inlet Catalyst Module

1. Reduce Harmful Emissions

The Inlet Catalyst Module contains precious metals (like platinum and palladium) that trigger chemical reactions:
CO (Carbon Monoxide) → converted into CO₂
HC (Hydrocarbons) → converted into CO₂ + H₂O
NO (Nitric Oxide) → partially converted into NO₂
These reactions make the exhaust cleaner before it enters the DPF or SCR system.

2. Support DPF Regeneration

The module helps increase exhaust gas temperature, which is crucial for burning off soot in the DPF.
Without a functioning Inlet Catalyst Module:
The DPF may clog faster
Regeneration cycles may fail or occur too often
The truck may enter limp mode

3. Protect Downstream Components

By oxidizing unburned fuel and stabilizing exhaust temperature:
It prevents fuel and soot buildup in the DPF.
It reduces stress on the SCR system and sensors.
It ensures the entire emissions system works efficiently.

4. Maintain Compliance and Performance

Required for meeting EPA and Euro emissions standards (such as EPA17+ for Cummins engines).
Keeps the engine in compliance with environmental regulations.
Helps maintain fuel efficiency and power output by keeping backpressure and exhaust flow stable.

1. Check Engine Light or Fault Codes

The ECM (Engine Control Module) will detect problems such as:
Low catalyst efficiency
Temperature sensor faults
Poor NOx or HC conversion
Common fault codes:
Cummins 3582, 1922, 2372, 2639, 3251 (related to DOC efficiency or temperature)
You’ll often see the Check Engine Light or Aftertreatment System Warning on the dashboard.

2. Excessive Soot or Smoke

If the catalyst isn’t oxidizing hydrocarbons properly:
You may see dark or black exhaust smoke.
Soot accumulates faster in the Diesel Particulate Filter (DPF).
This can cause frequent or failed DPF regenerations.

3. Poor DPF Regeneration or Frequent Regen Cycles

The Inlet Catalyst (DOC) helps heat the exhaust gases during DPF regeneration.
A bad DOC can’t maintain the temperature needed (~500–600 °C), causing:
Incomplete or failed regens
Increased soot load
“DPF Full” or “Regen Required” warnings

4. Reduced Engine Power or Limp Mode

The ECM may reduce engine power to protect the emissions system.
You’ll feel loss of acceleration, limited RPM, or the truck may enter limp mode.

5. Overheating or Unusual Exhaust Temperatures

A clogged or failing catalyst can restrict exhaust flow, causing:
High exhaust back pressure
Turbocharger overheating
Melted or damaged sensors
In severe cases, the module can glow red-hot or cause thermal damage to nearby components.

6. Strong Odors or Excessive Heat Near the Exhaust

A sulfur or burning smell may appear if the catalyst coating is damaged.
You might also notice excess heat near the DOC housing due to restricted flow.

7. Poor Fuel Economy

Because the system can’t efficiently process exhaust gases, the ECM compensates by injecting more fuel to maintain temperature or regeneration cycles.
This leads to higher fuel consumption over time.