Hino J08E 7.7L, 4JJ1, 4HK1 DEF Head Unit 2014-2024: OEM SG400-E0091

DEF Tank Sensor & Supply Module for Hino J08E, 4JJ1 & 4HK1 Engines (2014–2024)

What is it?
The Hino DEF Head Unit, identified by OEM SG400-E0091, is a tank-mounted component that manages both monitoring and delivery of Diesel Exhaust Fluid (DEF). Designed for engines produced between 2014 and 2024, this unit combines multiple functions into a single assembly, including fluid level detection, temperature monitoring, and DEF transfer to the aftertreatment system.

It serves as the interface between the DEF tank and the emissions system, helping ensure that fluid is properly measured and routed for NOx reduction.

Why choose this DEF Head Unit?
Modern SCR systems rely on accurate DEF data and steady fluid supply. The OEM SG400-E0091 unit is built for Hino J08E, 4JJ1, and 4HK1 platforms, helping maintain proper communication between the DEF tank and engine controls.

This assembly continuously tracks DEF condition and level, sending signals to the control module so the system can adjust dosing as needed. If the unit becomes faulty, it may lead to incorrect readings, warning lights, or reduced system function due to improper DEF management.

Replacing the head unit helps restore proper monitoring and ensures consistent DEF delivery throughout the emissions process.

Key Benefits
✅ OEM-matched DEF head unit for Hino J08E, 4JJ1, and 4HK1 engines
✅ Monitors DEF level, temperature, and system status
✅ Supports consistent DEF supply to the SCR system
✅ Helps maintain accurate communication with control modules
✅ 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 2014 through 2024. These engines are commonly found in medium-duty trucks, commercial fleets, and industrial equipment that rely on SCR systems for emissions compliance.

Installation Notes
Before beginning service, ensure the DEF tank level is low enough for safe removal. Disconnect electrical connectors and carefully remove the existing unit from the tank. Inspect seals, wiring, and the tank opening for contamination or crystallized DEF residue. 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-E0091) helps ensure accurate fluid tracking and steady supply, supporting consistent SCR operation and dependable engine function.