Dorman DEF Injector Gasket 904-085, OE-Style Direct Replacement with Resilient Seal

Dorman 904-085 is a direct-replacement diesel exhaust fluid (DEF) injector gasket designed to restore a proper seal when servicing the DEF injector.

This gasket is manufactured to match the fit and function of the original equipment part so you can reseal the injector port without modifying the vehicle. Made from resilient materials and validated through vehicle try-on testing, the Dorman 904-085 helps prevent fluid seepage and maintains the integrity of the DEF system after maintenance. Before ordering, verify vehicle compatibility using the garage/fitment tool to confirm a precise match for many Ford and Ram trucks.

How does this gasket restore the DEF injector during service?

When the DEF injector is removed for inspection or replacement, the original gasket can compress, tear, or lose sealing ability. Installing the Dorman 904-085 restores the original sealing surface and keeps DEF contained where it belongs, reducing the risk of leaks and contamination. The part is produced to the same geometry as the factory gasket to ease reassembly and maintain injector alignment.

• Exact OE-style shape for straightforward installation
• Material selected to resist DEF exposure and temperature cycles
• Minimizes downtime by fitting without alteration

Which vehicles will accept the Dorman 904-085 gasket?

This gasket fits a broad range of Ford Super Duty and F-series trucks and many Ram heavy-duty models across multiple years. Coverage includes F-150 through F-750 model lines for specific years, and Ram 2500–5500 vehicles from 2013 onward where applicable. Always use the site’s vehicle check tool and confirm the “Confirmed Fit” indicator to ensure compatibility with your exact model and trim.

• Ford: F-150, F-250/F-350/F-450/F-550/F-600, F-650/F-750 by listed years
• Ram: 2500, 3500, 4000, 4500, 5500 model year coverage as noted
• Use the garage tool and the blue “i” fitment notes for verification

What materials and testing back the gasket’s reliability?

Dorman constructs this gasket from materials chosen for resistance to DEF and repeated thermal cycling, providing a dependable sealing surface over time. The part undergoes vehicle try-on testing to validate fit, and Dorman’s long history in replacement parts supports consistent manufacturing standards. That testing helps ensure compatibility and reduces the chance of installation issues related to fit or dimensional differences.

• Durable elastomer and/or composite sealing materials
• Vehicle try-on testing for confirmed fit and function
• Manufactured under Dorman quality control processes

How do I install the DEF injector gasket and avoid problems?

Installation is straightforward for a technician or experienced DIYer: remove the old gasket, clean the mounting surface, seat the new gasket evenly, and torque the injector hardware to manufacturer specs. Take care to remove old sealant or debris that might prevent a full seat and verify the injector is aligned correctly before final tightening. If the Confirmed Fit tool shows fitment notes (blue “i”), review those details for any model-specific steps or additional parts required.

• Clean mating surfaces thoroughly before installation
• Seat gasket evenly and follow OEM torque specs
• Check fitment notes for model-specific instructions

Who this product is for: The Dorman 904-085 DEF injector gasket suits professional technicians, fleet maintenance teams, and owners of compatible Ford and Ram trucks who need a reliable, OE-style replacement when servicing the DEF injector. If you perform DEF injector maintenance or repair and want a proven replacement part that matches original fit and function, this gasket is intended to help you complete the job cleanly and quickly. Always confirm fitment for your exact model year and trim before purchase.