Volvo All Engines (2010 Emissions) Fault Code: SPN 4375 FMI 4 PID: PSID 121 Aftertreatment Diesel Exhaust Fluid Pump (DEF) Driver Percentage

The aftertreatment control module (ACM) uses the aftertreatment diesel exhaust fluid (DEF) dosing pressure sensor value to adjust and maintain DEF pressure at the DEF dosing valve by controlling DEF pump speed. If the pressure decreases below expected value when the pump is in initial pressure build-up mode or if the pressure increases above expected value when pump is in idle speed mode, the ACM considers DEF pressure outside of normal operating range and indicates a malfunction in a DEF dosing pressure sensor.

Conditions for diagnostic trouble code (DTC):
1) The voltage at pin A137:7 is below normal value

Observable symptoms
1) No aftertreatment diesel exhaust fluid (DEF) dosage

Probable cause
1) Short circuit to ground, Control wire (-)
2) Wiring harness
3) Aftertreatment Diesel Exhaust Fluid (DEF) Pump
4) Aftertreatment Control Module (ACM)

Detailed information
1) Possible engine de-rate