Safe to driveTo the nearest safe stop
J1939 code SPN 123. 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 0 | Mechanical fault of the large disengagement solenoid valve. Repair: Run the diagnostic check of the clutch actuator. Check the clutch. 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 0 | Mechanical fault in valve Y14. |
| SPN 123 FMI 0123/0 · 123.0 | data above normal range (most severe level) |
Safe to drive. Below — how much time you have and what happens if you keep going.
The gearbox or clutch has gone into limp mode: some gears may be unavailable and an automated box may stop shifting under load.
The main risk is being left on a climb with no gear and rolling back. Do not take a loaded truck into the hills; reaching level ground and a shop is fine.
That said, the manufacturer flags this code as critical — if in doubt, it is safer to stop and check on the spot.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.