Volvo All Engines (2013 Emissions) Fault Code: P20A300 PID: ACM Aftertreatment Reagent Direction Valve Short Circuit High

Circuit description
When ignition key is turned to OFF position the selective catalytic reduction (SCR) system enters afterrun mode. During afterrun, system attempts to drain diesel exhaust fluid (DEF) from the DEF dosing valve, DEF pump and DEF lines. Aftertreatment control module (ACM) activates DEF return valve by grounding the control wire (-). When the return valve is activated, the DEF reverses flow back to the tank, and DEF dosing pressure is expected to drop. If the dosing pressure does not drop or if it increases during afterrun, the return valve is considered to have a mechanical fault.

Conditions for diagnostic trouble code (DTC)
Short circuit to battery voltage on A137:12

Observable symptoms
Aftertreatment Diesel Exhaust Fluid (DEF) Pump After-run not possible

Probable cause
1) Connector
2) Wiring harness
3) Aftertreatment Diesel Exhaust Fluid (DEF) Pump
4) Aftertreatment Control Module (ACM)