Volvo All Engines (2013 Emissions) Fault Code: P20D712 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.

Conditions for diagnostic trouble code (DTC)
Current below normal or open circuit

Diagnostic operating conditions
Ignition key in ON position

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

Probable cause
1) Connector
2) Engine wiring harness
3) Aftertreatment fuel shut-off valve
4) Engine control module (ECM)