Volvo All Engines (2013 Emissions) Fault Code: P21CAA1 PID: ACM Reductant Control Module Supply Voltage

Circuit description
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)
The voltage at pin A137:62 is below normal value

Observable symptoms
No aftertreatment diesel exhaust fluid (DEF) dosage

Probable cause
1) Open circuit, Common voltage supply
2) Wiring harness
3) Aftertreatment Diesel Exhaust Fluid (DEF) Pump

Detailed information
Possible engine de-rate