International (Navistar)
J1939 SPN/FMI
SPN 4363 / FMI 21
International Fault Code SPN 4363 FMI 21: Aftertreatment 1 SCR Outlet Temperature: Data Drifted Low
SPN 4363 FMI 21 on International / Navistar trucks means: Aftertreatment 1 SCR Outlet Temperature: Data Drifted Low.
Code details
- Manufacturer
- International (Navistar)
- Applies to
- International A26 (2024–2025)
- Fault code
- SPN 4363 FMI 21
- J1939 SPN
- 4363
- FMI
- 21
- Truck models in source
- 3200, 4100, 4300, 4400, 7300, 7400, 7500, 7600, 7700, 8500, 8600, BE 200, CE Bus, CXT, DuraStar, LoneStar, MXT, ProStar, RXT, TranStar, WorkStar
What to do next
- Read active and inactive codes with the OEM service tool (Diamond Logic Builder can clear previously active codes) and note the occurrence count.
- FMI 21 tells the shop the type of failure to test for: .
- Have a heavy-duty diesel technician confirm the fault against the engine or chassis service manual before replacing parts.
Get this code diagnosed
Send one request and nearby diesel shops and mobile mechanics can quote the repair.
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Related fault codes
- International Fault Code SPN 4363 FMI 0 — Aftertreatment 1 SCR Outlet Temperature: Data Valid But Above Normal Operational Range – Most Severe Level
- International Fault Code SPN 4363 FMI 10 — Aftertreatment 1 SCR Outlet Temperature : Abnormal Rate Of Change
- International Fault Code SPN 4363 FMI 16 — Aftertreatment 1 SCR Outlet Temperature: Data Valid But Above Normal Operating Range – Moderately Severe Level
- International Fault Code SPN 4363 FMI 2 — Aftertreatment 1 SCR Outlet Temperature: Data Erratic, Intermittent Or Incorrect
- International Fault Code SPN 4363 FMI 20 — Aftertreatment 1 SCR Outlet Temperature: Data Drifted High
- International Fault Code SPN 4363 FMI 3 — Aftertreatment 1 Selective Catalyst Reduction (SCR) Outlet Temperature: Voltage Above Normal, Or Shorted To High Source
- International Fault Code SPN 4363 FMI 4 — Aftertreatment 1 SCR Outlet Temperature: Voltage Below Normal, Or Shorted To Low Source
- PACCAR Fault Code P3812 — Exhaust Gas Temperature After SCR Catalyst – Voltage Too High or Short Circuit to Supply
Source: International A26 2024–2025 fault code list (Diesel Laptops). See also OBD-II codes.