What this code means

Component / fault: Vehicle speed sensor.
Reported detail: loss of signal.
FMI 1 in the SAE J1939 / Caterpillar CDL convention means: Data valid but below normal operational range (most severe) — see the full FMI reference table.

On a Caterpillar display this code may appear as MID/CID 84 with FMI 1, 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)

The measured value itself is too low. Check the actual pressure / temperature / level first (leaks, low fluid, wear), then sensor plausibility.

These are general electrical checks for FMI 1 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 (84 / FMI 1), the machine model and serial number — we quote genuine and OEM replacement parts for export.

Same component, other failure modes

FMI 0 FMI 2 FMI 8 FMI 10 FMI 14