Check the def quality by using the refractometer from the def test kit w060589001900 to measure the def percentage. Websuspect parameter number (spn) and failure mode indicator (fmi) full code list. Webthis code sets when spn 521050/fmi 31 has been present for one hour of idle time, the vehicle has been restarted or six gallons of fuel has been used. Webnumber (spn), and failure mode indicator (fmi) descriptions this solution helps explain the underlying meaning of the numerical components which build a fault code. The learn procedure is done using powerlink. Webthe fmi is used along with the spn to provide specific information that relates to a diagnostic trouble code (dtc). The fmi may indicate that a problem with an electronic.
