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Volvo engine code DTC P20A1
Aftertreatment DEF Pump Direction Valve: Rationality Monitor After the ignition key is turned to the OFF position the aftertreatment control module (ACM) commands the aftertreatment diesel exhaust fluid (DEF) direction valve ON by grounding the control wire (-). When the aftertreatment DEF direction valve is activated, the DEF reverses flow back to the aftertreatment DEF tank, and aftertreatment DEF absolute pressure is expected to drop. During reverse DEF flow conditions on a pressurized selective catalytic reduction (SCR) system, pressure drop is evaluated. If DEF pressure drop is too low, the aftertreatment DEF direction valve is considered to have a mechanical fault (blocked or stuck). P20A1 Aftertreatment DEF Pump Direction Valve: Functional Check DTC P20A1 Component / System Direction Valve - Functional Monitor Strategy Description DEF pressure too high Fault Limit • DEF pressure > 950 kPa • Time above DEF pressure limit > 60 s Enable Conditions • Key Position Off • DEF System Purge Mode Disable Conditions No Active DTC's: • N/A Time Required For DTC To Be Set 60 Seconds (in after run) MIL Illumination 2 Drive Cycles