Safe to driveEnough to reach the yard
J1939 code SPN 3234. Below — how the fault is worded at the factory by DAF, and what the second half of the code (FMI) means in the standard.
| FMI 2 | NOx sensor F791 signal missing/implausible (extended period) |
| FMI 4 | NOx sensor F791 internal error (extended period) |
| FMI 9 | NOx sensor F791 CAN network communication error (extended period) |
| SPN 3234 FMI 23234/2 · 3234.2 | data erratic or intermittent |
| SPN 3234 FMI 43234/4 · 3234.4 | voltage below normal or shorted to ground |
| SPN 3234 FMI 93234/9 · 3234.9 | abnormal update rate |
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.
Fill the AdBlue tank. If it’s already full, the problem is dosing or reductant quality — you need a scanner.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.