2014 Volvo VNL670 D13 SPN 5392 fmi 31, SPN 5246 fmi 0 Codes

SPN 5392 fmi 31 After treatment diesel exhaust fluid (DEF) pressure build up failure Possible causes: Empty DEF tank DEF filter clogged (most likely the root cause) DEF inlet pipe leak or blockage DEF Pump assembly Spn 5246 fmi 0 means one or more DTC are set active in the after treatment and this code causes a 5 mph derate. Basically, focus on other codes to resolve issue