Safe to driveTo the nearest safe stop
J1939 code SPN 115. Below — how the fault is worded at the factory by International and ZF AS-Tronic, and what the second half of the code (FMI) means in the standard.
| FMI 2 | Alternator Current — Phase missing fault/alternator fault. |
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 | Shift lever fault. |
| SPN 115 FMI 0115/0 · 115.0 | data above normal range (most severe level) |
| SPN 115 FMI 2115/2 · 115.2 | data erratic or intermittent |
Safe to drive. Below — how much time you have and what happens if you keep going.
The electrical system is not holding voltage. While the engine runs the alternator carries it; shut it off and you may not restart.
Next the lights go, then modules start dropping out and false codes appear all over the truck. Get to somewhere with help without shutting the engine down.
That said, the manufacturer flags this code as critical — if in doubt, it is safer to stop and check on the spot.
Check the battery terminals and earth strap — corrosion and loose clamps throw false codes all over the truck. Running voltage should be 27–29 V.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.