What this code means

Component / fault: J1939 data.
Reported detail: incorrect data fron J1939.
FMI 2 in the SAE J1939 / Caterpillar CDL convention means: Data erratic, intermittent or incorrect — see the full FMI reference table.

On a Caterpillar display this code may appear as MID/CID 231 with FMI 2, or in the older PID/SID style. Wording of the reported detail follows the public Caterpillar fault-code listing cited below.

First checks (general, for this failure type)

Signal is intermittent. Wiggle-test the harness, inspect connector pins for spread or corrosion, and look for chafed wires at rub points.

These are general electrical checks for FMI 2 faults, not a substitute for the model-specific test procedure. If the fault is active and the machine is derated or shut down, follow the service manual for your model and serial prefix.

Need the part?

If the checks point to a failed sensor, solenoid or harness part, send us the code (231 / FMI 2), the machine model and serial number — we quote genuine and OEM replacement parts for export.

Same component, other failure modes

FMI 11 FMI 12 FMI 14