Diesel fault codes
Look up OBD-II and SAE J1939 diesel fault codes — what each one means, likely causes, and how urgent it is.
scr codes
SPN 1761 / FMI 1
DEF Tank Level — Below Normal (Most Severe)
scrHigh
SPN 1761 / FMI 3
DEF Tank Level Sensor — Voltage High
scrLow
SPN 3216 / FMI 2
Aftertreatment Intake NOx — Data Erratic
scrMedium
SPN 3226 / FMI 2
Aftertreatment Outlet NOx — Data Erratic
scrMedium
SPN 3361 / FMI 5
DEF Dosing Unit — Current Below Normal/Open
scrHigh
SPN 3364 / FMI 1
DEF Quality — Below Normal
scrHigh
SPN 4094 / FMI 0
SCR Operator Inducement — Severe
scrCritical
SPN 4334 / FMI 1
DEF Dosing Pressure — Below Normal
scrHigh
SPN 4364 / FMI 18
SCR Conversion Efficiency — Low (Moderate)
scrHigh
P203B
Reductant Level Sensor Performance
scrMedium
P204F
Reductant System Performance
scrHigh
P205B
Reductant Tank Temperature Sensor Circuit High
scrLow
P20E8
Reductant Pressure Too Low
scrHigh
P20EE
SCR NOx Catalyst Efficiency Below Threshold (Bank 1)
scrCritical
P2201
NOx Sensor Circuit (Bank 1 Sensor 1)
scrHigh