Hino J08E 7.7L, 4JJ1, 4HK1 DEF Head Unit 2010-2015: OEM SG400-E0022

DEF Tank Monitoring & Supply Assembly for Hino J08E, 4JJ1 & 4HK1 (2010–2015)

What is it?
The Hino DEF Head Unit, identified by OEM SG400-E0022, is a tank-mounted module designed for engines produced between 2010 and 2015. This component serves as the central point for managing Diesel Exhaust Fluid (DEF) inside the tank, combining multiple functions such as fluid level sensing, temperature monitoring, and DEF transfer into one assembly.

Positioned at the top of the DEF tank, it connects directly to the emissions system, helping ensure fluid is properly measured and delivered to support NOx reduction through the SCR process.

Why choose this DEF Head Unit?
SCR systems depend on accurate DEF data and steady fluid delivery to operate correctly. The OEM SG400-E0022 unit is built for Hino J08E, Isuzu 4JJ1, and 4HK1 engine platforms, helping maintain proper communication between the DEF tank and the engine control module (ECM).

This module continuously tracks DEF condition—including level and temperature—and sends real-time signals to the ECM so the system can adjust dosing as needed. When the unit becomes faulty, it can lead to incorrect readings, warning alerts, or reduced emissions system efficiency due to improper DEF supply.

Replacing the head unit helps restore proper system feedback and ensures the SCR system receives the correct amount of fluid for consistent operation.

Key Benefits
✅ OEM-matched DEF head unit for Hino J08E, 4JJ1, and 4HK1 engines
✅ Monitors DEF level, temperature, and system status
✅ Supports steady DEF delivery to the aftertreatment system
✅ Helps maintain accurate ECM communication
✅ Direct-fit design for secure tank installation

Applications
This DEF head unit is used on diesel engines equipped with Hino J08E 7.7L, Isuzu 4JJ1, and 4HK1 platforms manufactured from 2010 through 2015. These engines are commonly found in medium-duty trucks, delivery vehicles, and commercial fleets that rely on SCR systems for emissions compliance.

Installation Notes
Before starting service, ensure the DEF tank level is low enough for safe removal. Disconnect the electrical connectors and carefully remove the existing unit from the tank. Inspect seals, wiring, and the tank opening for contamination or DEF residue buildup. Install the replacement unit with proper sealing, reconnect all connections, and verify system readings using diagnostic tools.

Final Thoughts
Proper DEF monitoring and delivery are essential for maintaining emissions system performance. The Hino DEF Head Unit (OEM SG400-E0022) helps ensure accurate fluid tracking and consistent supply, supporting reliable SCR operation and stable engine performance.