Nitrogen Oxide / NOx Sensor ~ Inlet | Cummins 4326870 / 2872944 / 3687930 | FleetRun FR-AFTR551


Same Day Shipping

Order The Truck Parts You Need Now and Pay Later With Our Financing Option Available

Order Now, Pay Later

Need Help With Parts?

(872) 240-4144

Hassle Free Returns

6 Month / 50,000 Mile Warranty

Part Number

  • FleetRun: FR-AFTR551

Cross Reference Part Number

  • Cummins: 4326870 / 2872944 / 3687930 / 3687930RX / 4326870RXCUM / 3687930RXCUM / 3687930CUM
  • Automann: 577.90656
  • Misc. Industry Part Number: 5WK9 6740B


  • Inlet Sensor
  • Mounting Hole Center To Center Length: 3.56 in.
  • Mounting Hole Diameter: 0.31 in.
  • Sensor Thread Side: M20-1.5
  • Voltage: 12v
  • Wire Harness Length: 620 mm / 20.40 in.
  • Wire Gauge Measurement: 20 AWG
  • 4 Pin Connector
  • Connector Shape: Rounded Square
  • Female Connector

Please note: this is an aftermarket part, the use of other manufacturer's names, part numbers or trademarks is for informational purposes only.

Please verify OEM part numbers before purchasing, FleetRun assumes no liability related to product use and fitment.

Introducing the FleetRun FR-AFTR551 NOx Sensor - the ultimate solution for all your Cummins aftertreatment and emissions needs. Whether you're a truck owner, operator, or mechanic, this sensor is an essential part of your vehicle's system and will ensure your truck runs at peak performance.

NOx Sensors, also known as Nitrogen Oxide Sensors are a part of the aftertreatment / emissions system of various tractors/trucks and may be specific to a certain year, make, and model of the application.

With a part number 3687930RXCUM, this sensor is a direct replacement for the OEM part number 4326870 and is compatible with a wide range of Cummins engines. It features a 4-pin connector, 12v voltage, and a wire harness length of 620mm. The sensor thread is M20-1.5 and the wire gauge measurement is 20 AWG. The sensor is a female connector, with a rounded square shape.

This product is designed to withstand the toughest of conditions, and the NOx sensor is manufactured to meet or exceed OEM standards. With its superior quality, it is a must-have item for any business that relies on a fleet of trucks.

The installation process of this sensor is straightforward and can be easily accomplished by a qualified mechanic. And in case you need any help, our website resources are available 24/7 for you to use or you can give us a call 7 days a week for dealer-level support.

At FleetRun, we understand the importance of timely repair and maintenance of your truck, which is why we offer competitive pricing on all our products. We believe that purchasing high-quality parts should not break the bank, and that is why we offer the best prices in the market.

We also understand the importance of customer feedback, which is why we encourage our customers to leave reviews on our website. We value your feedback and use it to improve our products and services.

  • For other information such as tips and tricks or troubleshooting from technicians and shops visit our Shop Talk page from our menu

Is there a difference between OEM and aftermarket NOx sensors for Cummins ISX engines?

When it comes to NOx sensors for Cummins ISX engines, there can be a significant difference between OEM and aftermarket options. OEM sensors, or original equipment manufacturer sensors, are manufactured by the same company that built your engine. These sensors are designed specifically for your engine and typically meet the highest standards for quality and performance. However, OEM sensors can be quite expensive and may not always be readily available.

On the other hand, aftermarket NOx sensors are manufactured by third-party companies and may not always meet the same quality standards as OEM sensors. This can lead to issues with performance and longevity.

At FleetRun, we understand the importance of high-quality, reliable NOx sensors for your Cummins ISX engine. That's why we offer an aftermarket NOx sensor that is designed to meet or exceed OEM standards. Our NOx sensors are rigorously tested to ensure they meet the highest standards for performance and longevity. And unlike OEM sensors, our aftermarket sensors come at a reasonable price, so you can save money without sacrificing quality. Furthermore, we offer after-sale support and deliver the parts to the customer's door for a convenient experience. So, when you choose FleetRun, you can rest assured that you are getting a quality product at an affordable price, and with excellent support.