Safe to driveEnough to reach the yard
J1939 code SPN 1231. Below — how the fault is worded at the factory by International, KAMAZ, MAZ, Renault Trucks, SITRAK and YaMZ, and what the second half of the code (FMI) means in the standard.
InternationalKAMAZMAZRenault TrucksSITRAKYaMZ
| FMI 9 | Body Address Claim/Message Timeout — J1939 Body Builder Data Link Lost |
| FMI 14 | Body Address Claim/Message Timeout — Global Broadcast Messages, J1939, proprietary, private bus (body builder) (address 255) has an unknown fault. |
| FMI 12 | ⚠ CAN bus B off-line (bus-off) |
| FMI 12 | CAN line B missing - Bus disconnected. Blink code: 4-1-2. Repair: Check the CAN bus connection to the other CAN devices. |
| FMI 9 | CAN bus in the OFF state, or the bus tester is faulty. Repair: CAN bus problem, check the wiring (B 8, B 39). Check the wiring (J 2/8, J 2/39). |
| FMI 12 | CAN2 broadcast message error |
| FMI 13 | CAN2 address conflict |
| FMI 12 | CAN line B missing (Bus disconnected). Blink code: 4-1-2. Repair: Check the CAN bus connection to the other CAN devices. |
Safe to drive. Below — how much time you have and what happens if you keep going.
The modules have stopped hearing each other on the bus. Some dash readings are now made up and some functions are simply off.
You can physically drive, but do not trust the instruments, and the other codes in the list may well be false: fix the bus first, then look at the rest.
Check connectors and the harness: a broken CAN twisted pair takes out communication for every ECU at once.
These normally light up after this code:
They are not fixed separately — they go out together with this one. The list is deliberately short: only the links the reference is sure about.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.