Safe to driveEnough to reach the yard
J1939 code SPN 1237. Below — how the fault is worded at the factory by Mercedes-Benz, and what the second half of the code (FMI) means in the standard.
| FMI 4 | Stop Engine Override Switch shorted to Ground (if applied more than 5 sec this error flags) |
| SPN 1237 FMI 41237/4 · 1237.4 | voltage below normal or shorted to ground |
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.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.