E-ONE Cummins ISL DEF Head Unit

Reliable DEF Control for Industrial Duty: E‑ONE Cummins ISL DEF Head Unit (OEM 077905V019)

What is it?
The E-ONE Cummins ISL DEF Head Unit (OEM 077905V019) is a control module for the Diesel Exhaust Fluid (DEF) system in E-ONE vehicles equipped with the Cummins ISL engine. This unit manages DEF level monitoring, temperature sensing, dosing of reductant into the exhaust flow, and communicates signals to the engine control/emissions system to enable the Selective Catalytic Reduction (SCR) process.

Why Choose this E-ONE Cummins ISL DEF Head Unit (OEM 077905V019)?
Built to exact OEM specifications for E-ONE chassis with the Cummins ISL engine, this head unit aligns with factory mount points, ports, connectors and wiring layout. Using an OEM-matched unit ensures proper fitment, reliable sensor integration, correct DEF system behaviour and helps avoid installation mismatches or emission faults in demanding duty-cycle conditions.

Key Benefits
✅ Factory-Matched Fit: Compatible with the original mounting, fluid/sensor interfaces and exhaust system layout.
✅ Heavy-Duty Construction: Engineered to withstand harsh operating conditions, frequent engine cycles and DEF system demands typical of fire apparatus or industrial vehicles.
✅ Accurate DEF Monitoring & Dosing: Ensures the SCR system receives the correct fluid volume, temperature and sensor data for NOₓ reduction.
✅ Reduced Risk of Faults and Derates: Using the correct head unit helps avoid DEF system error codes and emission-control related derates.
✅ System Longevity: Proper DEF dosing and sensor operation helps protect downstream SCR catalyst, sensors and exhaust hardware from undue stress.

Applications
This head unit applies to E-ONE vehicles (aerial trucks, pumpers, rescue units, tankers) powered by Cummins ISL engines that use DEF and SCR systems. It’s especially beneficial for heavy-duty, industrial or emergency-response equipment where reliability and emission compliance matter.

Installation Notes
Installation should be handled by a qualified technician familiar with SCR and DEF systems. First, confirm the engine model, serial year and verify that OEM number 077905V019 matches your configuration. Depressurize and drain any residual DEF fluid if necessary, disconnect wiring, and remove the old head unit while noting mounting layout, sensor connections and fluid ports. Clean the mating surfaces, inspect gaskets or seals for wear, and install the new unit with correct bolt torque and alignment. Re-connect sensors and wiring harnesses, clear any diagnostic fault codes, and run a controlled system check to confirm DEF level accuracy, sensor signals and SCR system behaviour before returning to full duty.

Final Thoughts
Accurate DEF head-unit performance is crucial for modern emission systems. The E-ONE Cummins ISL DEF Head Unit (OEM 077905V019) provides a factory-correct replacement option that helps restore DEF system integrity, maintain emission compliance and keep your vehicle running reliably in demanding conditions.