EA4710700055 | Genuine Detroit Diesel® Doser Metering Unit

• The doser measures the exact amount of DEF needed based on engine load, speed, and temperature.

• This ensures efficient NOx reduction and prevents over- or under-injection.

2. Injects DEF Into the Exhaust

• Delivers DEF into the exhaust pipe upstream of the SCR catalyst.

• The fluid reacts with NOx in the catalyst to form harmless nitrogen and water.

3. Maintains Proper DEF Pressure

• The doser has an internal metering pump and pressure control.

• Keeps DEF injection steady and accurate, even with temperature changes or vehicle movement.

4. Communicates With the Engine ECM

• Receives commands from the engine control module (ECM) about how much DEF to inject.

• Sends back information on flow rate, pressure, and temperature for monitoring and fault detection.

5. Helps With Emissions Compliance

• Accurate dosing ensures the vehicle meets EPA or Euro emission standards.

• Prevents engine derate or SCR system warnings caused by over- or under-injection.

1. Inconsistent or Inaccurate Dosing

• The unit dispenses too much or too little chemical.

• Variations in chemical concentration despite unchanged settings.

• This is often due to worn pump diaphragms, clogged valves, or calibration drift.

2. Unusual Noises

• Humming, grinding, or rattling sounds from the motor or pump.

• Could indicate mechanical wear, air in the lines, or failing bearings.

3. Leaks

• Chemical leaking from connections, hoses, or the pump.

• Leaks suggest damaged seals, cracked housings, or loose fittings.

4. Pump Not Operating

• No flow even when the system is turned on.

• Could be caused by electrical issues, burned-out motor, or clogged suction lines.

5. Pressure Fluctuations

• Pressure readings inconsistent or dropping suddenly.

• Could indicate blockages, air locks, or failing pump components.

6. Erratic Control Signals

• The control system shows errors, alarms, or inconsistent readings.

• Often a sign of sensor failure, wiring issues, or internal electronic faults.

7. Visible Wear and Tear

• Cracks, corrosion, or chemical residue buildup.

• These can reduce performance or eventually lead to mechanical failure.

8. Reduced Flow Rate

• Even with proper settings, flow is below expected.

• Could be worn diaphragms, clogged suction filters, or deteriorated check valves.