SPN 4364 FMI 1 Means, Causes & Fix
SPN 4364 FMI 1 indicates an exhaust gas temperature signal that is lower than expected, often leading to regen issues, derates, or warning lights. This guide explains common causes such as wiring damage, connector corrosion, exhaust leaks, and sensor drift, along with a structured troubleshooting process to help you identify the real fault, avoid unnecessary parts replacement, and restore stable engine and aftertreatment performance.












