Volvo All Engines (2013 Emissions) Fault Code: P20D900 PID: EMS Exhaust Aftertreatment Fuel Supply Control

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.

Conditions for diagnostic trouble code (DTC):
1) Voltage below normal or shorted low

Diagnostic operating conditions
1) Ignition key in ON position

Observable symptoms
1) Regeneration not possible
2) Aftertreatment selective catalytic reduction (SCR) catalyst warming not possible

Probable cause
1) Connector
2) Short circuit to ground
3) Engine wiring harness
4) Wiring harness
5) Engine Control Module (ECM)