Cummins code spn 4364 fmi 18. One small issue like Spn 4364 Fmi 18 can cause a larger component to become damaged without taking the time to investigate. Get the SCR doser valve gasket, then pull it off and see if it's caked up with dried DEF. I have access to Quickserve and Insite. Nov 4, 2024 ยท The SPN 4364 code indicates a problem with the Aftertreatment SCR (Selective Catalytic Reduction) Conversion Efficiency in diesel engines. I noticed the ECM update changed the shift points to a slightly higher RPM before they shift, and stays in 5th gear longer. Fault is SPN 4364 FMI 18 - Aftertreatment SCR Catalyst Conversion Efficiency - Data Valid but Below Normal Operating Range - Moderately Severe Level. If you don't take the time to look into Spn 4364 Fmi 18 engine problem when it arises, it can add up quickly. The first step is to connect your Diagnostic tool to see what other codes have been triggered. If you suspect your truck is suffering from one of these issues, look into replacing those small components to save money down the road. When was the last time you cleaned the DEF doser? If you never have, it's probably overdue. aufbz kftn ruj xewjt whgvp hph fap yfuql vbselq zurqclp