International Fault Code SPN 5031 FMI 2: Aftertreatment 1 Outlet NOx Sensor Heater Ratio : Data Erratic, Intermittent Or Incorrect

Code details

Manufacturer

International (Navistar)

Applies to

International A26 (2024–2025)

Fault code

SPN 5031 FMI 2

J1939 SPN

5031

FMI

2 — Data erratic, intermittent or incorrect

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 2 tells the shop the type of failure to test for: data erratic, intermittent or incorrect.
• Have a heavy-duty diesel technician confirm the fault against the engine or chassis service manual before replacing parts.

Related fault codes

• International Fault Code SPN 5031 FMI 10 — Aftertreatment 1 Outlet NOx Sensor Heater Ratio: Abnormal Rate of Change
• PACCAR Fault Code P3915 — NOx Sensor After Catalyst – Heating Error
• PACCAR Fault Code P3927 — NOx Sensor After Catalyst – Data Valid But Too High
• PACCAR Fault Code P3915 — Heater Element NOx Sensor After Catalyst – Warm-Up Failed
• PACCAR Fault Code P3927 — Heater Element NOx Sensor After Catalyst Performance – Malfunction