Volvo All Engines (2017 Emissions) Fault Code: P20D773 PID: EMS Exhaust Aftertreatment Fuel Supply Control

Volvo All Engines (2017 Emissions) Fault Code: P20D773 PID: EMS Exhaust Aftertreatment Fuel Supply Control

Circuit description
The Aftertreatment Hydrocarbon Dosing Module contains three non serviceable valves, the Aftertreatment Fuel Shutoff Valve, Aftertreatment Purge Air Valve and Aftertreatment Hydrocarbon Dosing Valve, and a serviceable Aftertreatment Fuel Pressure Sensor.

During DPF regeneration the Engine Control Module (ECM) sends a voltage signal to activate the Aftertreatment Fuel Shutoff Valve to the open position. This allows fuel to flow into the Aftertreament Hydrocarbon Dosing Module. The Aftertreatment Fuel Pressure Sensor monitors the fuel pressure value and sends a reference signal to the ECM. The ECM then sends a PWM signal to the Aftertreatment Hydrocarbon Dosing Valve that regulates the amount of fuel delivered to the Aftertreatment Hydrocarbon Doser through the air/fuel line.

During Air Purge operation the Engine Control Module (ECM) sends a voltage signal to activate the Aftertreatment Purge Air Valve open. This allows air pressure to flow into the Aftertreament Hydrocarbon Dosing Module. The ECM then sends a PWM signal to the Aftertreatment Hydrocarbon Dosing Valve that allows purge air pressure to be monitored by a signal from the Aftertreatment Fuel Pressure Sensor to the ECM.

Conditions for diagnostic trouble code (DTC)
Aftertreatment Fuel Pressure, not within expected range
Fuel pressure fault

Observable symptoms
Regeneration not possible

Probable cause
1) Fuel pressure
2) Fuel line(s)
3) Aftertreatment Hydrocarbon Dosing Module