Safe to driveEnough to reach the yard
J1939 code SPN 173. Below — how the fault is worded at the factory by Renault Trucks and ZF AS-Tronic, and what the second half of the code (FMI) means in the standard.
| FMI 8 | Erroneous “brake pedal pressed” signal. Repair: Run the diagnostic check of the EBS unit. Check the programming. Check the brake pedal. Run the diagnostic check of the VECU. Switch the ignition off, switch it on again and repeat the test. If the fault persists, replace the control unit. |
ZF AS-Tronic uses its own fault numbering: the number in the table below is an internal ZF code, not a J1939 SPN. It matches the title of this page by digit only and means something different.
| FMI 8 | No signal from the brake sensor. |
| SPN 173 FMI 8173/8 · 173.8 | abnormal frequency or pulse width |
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.