VOLVOUU All Engines (2017 Emissions) Fault Code: P20E797 PID: ACM Reductant Injection Air Pressure Too High

VOLVOUU All Engines (2017 Emissions) Fault Code: P20E797 PID: ACM Reductant Injection Air Pressure Too High

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 duty cycle is lower than expected
The air pressure decreases slower than expected when the air valve has been closed

Observable symptoms
Possible engine de-rate

Probable cause
1) Nozzle (Air circuit)
2) Air line
3) Crystals in the Aftertreatment Diesel Exhaust Fluid (DEF) mixing tube
4) Aftertreatment diesel exhaust fluid (DEF) pump

Detailed information
Crystallized Aftertreatment Diesel Exhaust Fluid (DEF) indicates that the overflow valve is leaking DEF solution backwards
To fully verify the repair it may be necessary to activate vehicle functions or perform a test drive