Safe to driveEnough to reach the yard
J1939 code SPN 4094. Below — how the fault is worded at the factory by Foton, Knorr-Bremse EBS and MAN, and what the second half of the code (FMI) means in the standard.
| FMI 31 | DPF regeneration required |
| FMI 0 | Wear indicators brake pads, wheel 8, large difference signal. Undefined fault |
| FMI 0 | Wear indicators brake pads, wheel 8, large difference signal. Undefined fault |
| SPN 4094 FMI 04094/0 · 4094.0 | data above normal range (most severe level) |
| SPN 4094 FMI 314094/31 · 4094.31 | condition exists (see manufacturer description) |
Safe to drive. Below — how much time you have and what happens if you keep going.
Urea dosing is interrupted and the ECU is counting. First the lamp, then a torque cut, then a forced crawl speed — the stages come in by engine hours, not all at once.
The truck will not die mid-highway, but the window shrinks with every running hour. Plan the repair now, not when the power is gone: an emulator or "deleting AdBlue" does not remove the problem, the codes keep stacking.
That said, the manufacturer flags this code as critical — if in doubt, it is safer to stop and check on the spot.
Fill the AdBlue tank. If it’s already full, the problem is dosing or reductant quality — you need a scanner.
This code is often not the fault itself but a knock-on. If any of these is in the same readout, start with it:
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.