Dorman 904-394 Diesel Exhaust Fluid (DEF) Heater

Dorman 904-394 DEF Heater for Silverado and Sierra HD

Dorman 904-394 is a diesel exhaust fluid (DEF) heater built for specific GM heavy-duty diesel applications. It addresses a common factory failure point caused by fluid intrusion and uses an OE FIX design to improve reliability in service.

Compatible with 2012-2016 Chevrolet Silverado 2500 HD, 2012-2016 Chevrolet Silverado 3500 HD, 2012-2016 GMC Sierra 2500 HD, and 2012-2016 GMC Sierra 3500 HD.

• Specific-fit DEF heater for select Chevrolet Silverado HD and GMC Sierra HD diesel trucks
• OE FIX design modifies the original heater layout to help reduce repeat failure from fluid intrusion
• Plastic housing with black finish for application-specific packaging
• Female inlet and outlet fittings for direct replacement use
• Includes integrated level sensor type: resistor
• Electrical connector configuration: 2 connectors with male/female terminals
• Mounting hardware included for installation

Detailed Product Overview

This Dorman DEF heater is engineered for diesel exhaust fluid system service on select GM heavy-duty trucks. The part number 904-394 is designed around the original equipment application and updates the factory design to address a known intrusion-related failure mode. It is a direct-fit emission control component for Silverado 2500 HD, Silverado 3500 HD, Sierra 2500 HD, and Sierra 3500 HD models from 2012 through 2016.

Built with a plastic housing and specific-fit dimensions, this heater uses female inlet and outlet fittings and a resistor-style level sensor. The connector layout includes two electrical connectors with male/female terminal arrangements, supporting the vehicle’s DEF system interface. This part cross-references Standard Ignition DFH106 for the same application.

Common DEF System Issues

• DEF heater failure caused by fluid intrusion into the factory unit
• Warning lights related to DEF temperature or heater circuit faults
• Cold-weather DEF system performance problems
• Reduced DEF tank heating efficiency in diesel emission systems
• Service codes tied to heater or level sensor circuit concerns

Installation Notes and Tips

Verify connector style, inlet and outlet orientation, and vehicle application before installation. This part is specific fit for 2012-2016 Chevrolet Silverado 2500 HD, 2012-2016 Chevrolet Silverado 3500 HD, 2012-2016 GMC Sierra 2500 HD, and 2012-2016 GMC Sierra 3500 HD. Follow factory service procedures for DEF system draining, electrical connection, and sealing checks to help prevent contamination during replacement.

Quality Assurance

Dorman OE FIX components are developed to address known weaknesses in original designs while maintaining application-specific fitment. Part number 904-394 is built as a direct replacement solution for select GM diesel trucks and is backed by Dorman’s product engineering approach for emission control service parts.