What does SPN 3221 FMI 12 (3221/12) mean?

Aftertreatment 1 Intake Wide-Range O2 Sensor Reading Stable: faulty device or component.

What does SPN 3221 FMI 15 (3221/15) mean?

Aftertreatment 1 Intake Wide-Range O2 Sensor Reading Stable: above normal — low severity.

Safe to drive. Below — how much time you have and what happens if you keep going.

Safe to driveUntil the next service

J1939 code SPN 3221. Below — how the fault is worded at the factory by SITRAK, and what the second half of the code (FMI) means in the standard.

FMI 12	Loss of CAN communication with UEGO sensor
FMI 15	UEGO sensor out of reasonable range, class 1
FMI 16	UEGO sensor out of reasonable range, class 2
FMI 31	UEGO sensor internal processor fault

SPN 3221 FMI 123221/12 · 3221.12	faulty device or component
SPN 3221 FMI 153221/15 · 3221.15	above normal — low severity
SPN 3221 FMI 163221/16 · 3221.16	above normal — moderate severity
SPN 3221 FMI 313221/31 · 3221.31	condition exists (see manufacturer description)

Safe to drive. Below — how much time you have and what happens if you keep going.

Time you have: Until the next service

A standalone fault with no immediate consequences for driving.

Show the codes at the next service. If a second code from the same system appears, stop putting it off.

Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.