FMI 20 — Data drifted high
The value has slowly crept higher than expected over time.
What it typically points to
Sensor aging, contamination, or an offset problem.
Codes with FMI 20
- SPN 3216 FMI 20Aftertreatment 1 Intake NOx
- SPN 3226 FMI 20Aftertreatment 1 Outlet NOx