Volvo All Engines (2013 Emissions) Fault Code: P20A500 PID: ACM Reductant Purge Control Valve Stuck Closed

Circuit description
This function is used to calculate the EGR Mass Flow. The Engine Control Module (ECM) monitors the EGR differential pressure sensor and the EGR temperature sensor after cooler and uses these signals to calculate the EGR Mass Flow data.

Conditions for diagnostic trouble code (DTC)
The air valve must provide approximately 300?kPa (43.5?psi) air pressure
The non-return valve must be opened above 300?kPa (43.5?psi)
The DEF pressure sensor does not measure air pressure when overflow valve should be opened

Probable cause
1) Air supply
2) Overflow valve

Detailed information
To fully verify the repair it may be necessary to activate vehicle functions or perform a test drive