School Bus DEF Products

DEF Header Solutions Built for Bus Fleet Reliability

Thomas Built®, Freightliner®, IC®/International®, and Blue Bird®

When DEF system downtime keeps your buses off the road and maintenance costs climbing, it’s time to rethink your DEF header and sensor solution. DuraWRX™ DEF headers are engineered to restore confidence in your emissions system—delivering durability, accuracy, and long‑term uptime across today’s most common school and transit bus platforms.

Important Note:
DuraWRX™ replacement DEF headers may differ in appearance from original equipment (OE) parts. However, every DuraWRX™ design adheres strictly to OE specifications for fit, form, and function, ensuring seamless installation and reliable performance.

Why DEF Headers Matter More Than Ever

DEF header failures are a leading cause of derates, check‑engine lights, and unexpected service calls. Inconsistent sensor readings, freeze‑related damage, and harsh operating environments can cripple productivity.

DuraWRX™ DEF headers are designed to solve these challenges head‑on—helping fleets:

• Reduce downtime caused by faulty DEF sensors
• Improve cold‑weather reliability
• Maintain emissions compliance
• Lower overall maintenance costs

At the heart of every DuraWRX™ DEF system is a robust, intelligent design built for real‑world fleet conditions.

The Heart of the DuraWRX™ DEF System

Below is a comprehensive overview of DuraWRX™ DEF header solutions by application, including year range, tank size, sensor type, engine compatibility, and OE cross‑references.

Thomas Built® / Freightliner® Applications

ASPFL‑2336

• Years: 2010–2016
• Tank Size: 6 Gallon
• Sensor Output: Analog
• Engine: Cummins
• OE Cross References: 04‑30774‑001 / 04‑30774‑005

ASPFL‑2324

• Years: 2017–2024
• Tank Size: 6 Gallon
• Sensor Output: Digital
• Engine: Cummins
• OE Cross References: 04‑31354‑002 / 04‑31354‑003 / 04‑31354‑004

ASPFL‑2335

• Years: 2017–2024
• Tank Size: 6 Gallon
• Sensor Output: Analog
• Engine: Detroit Diesel
• OE Cross References: 04‑30774‑000 / 04‑30774‑004

ASPFL‑2325

• Years: 2017–2020
• Tank Size: 13 Gallon
• Sensor Output: Analog
• Engine: Detroit Diesel
• OE Cross References:
  04‑31677‑000 / 04‑30798‑000 / 04‑27881‑000 / 04‑31893‑000

ASPFL‑2327

• Years: 2021–2024
• Tank Size: 13 Gallon
• Sensor Output: Analog
• Engine: Detroit Diesel
• OE Cross References: 04‑33656‑000

IC® / International® Applications

ASP‑908‑2317‑449

• Years: 2014–2024
• Tank Sizes: 7 Gallon, 15 Gallon
• Sensor Output: Digital
• Engine: Cummins
• OE Cross References:
  602065 / 601968 / 5511563 / 5511560 / 4378045 / 5511565 / 4378050 /
  5510447 / 1DFQ‑70300 / 70029009 / 70026277 / 4254215C91 / 4097725C91 /
  4087160C91 / 4163693C91 / 4086806C91 / 2523590C91 / 4097724C91 /
  2515988C3 / A000P868

Blue Bird® Applications

ASP5310‑6606718

• Years: 2010–2017
• Tank Size: 15 Gallon
• Sensor Output: Analog
• Engine: Cummins
• OE Cross References:
  10019935 / 10027844 / 10035950 / 10056545 / 5011806

ASP4310‑6600718

• Years: 2018–2024
• Sensor Output: Digital
• Engine: Cummins
• OE Cross References:
  10049766 / 10060598 / 10071997 / 46697828 / 46858813 / DEP106308 /
  4812011675 / 4812073636 / 82‑67123‑000 / 82‑88414‑000 / 83‑01116‑000 /
  83‑09271‑000 / 924532.0004 / 853030189 / 853030184 / SP199819 /
  60C3325 / 50220849 / 50312250 / 1554670 / 1604688 / 3136685 /
  3350441 / TR1700‑634‑01 / 502373 / 185152 / 066900101

Engineered Advantages of DuraWRX™ DEF Headers

Every DuraWRX™ DEF header is designed with performance, durability, and compliance in mind:

• OEM‑compliant design meeting all regulatory and manufacturer specifications
• Extreme cold capability, with integrated heating technology capable of thawing DEF at temperatures as low as ‑40°F (‑40°C)
• Advanced ultrasonic sensing technology that minimizes false readings and nuisance faults
• Full compatibility with today’s major DEF dosing units
• Backed by a full 2‑year warranty for added confidence

Keep Your Buses Moving

If DEF‑related failures are impacting uptime, DuraWRX™ offers a proven, fleet‑friendly solution. Built for demanding environments and backed by engineering you can trust, DuraWRX™ DEF headers help keep buses where they belong—on the road, not in the shop.

View all of our DuraWRX DEF products (Click Here)