Do not driveMinutes
J1939 code SPN 986. Below — how the fault is worded at the factory by International, Mercedes-Benz and SITRAK, and what the second half of the code (FMI) means in the standard.
InternationalMercedes-BenzSITRAK
| FMI 2 | Requested Percent Fan Speed — Engine Fan Switch Error |
| FMI 9 | J1939 CM1 DPF Message is missing or not available |
| FMI 13 | J1939 CM1 Fan SPN986 Signal from source address #1 or #2 is missing or not available = SNA (signal not available) |
| FMI 19 | J1939 CM1 Fan SPN986 Signal from source address #1 or #2 is erractic = undefined value but not SNA |
| FMI 19 | Incorrect data length of the CM1 CAN frame. Effect: Loss of communication with the modules, some functions are disabled. |
Do not drive. Stop as soon as it’s safe to do so — don’t keep going.
The engine is already past its temperature limit. An aluminium head goes fast: first the geometry warps, then the gasket burns through.
Next comes a blown head gasket, a damaged head and, at worst, a cracked block. Shut it down and let it cool — never open the expansion tank cap while hot.
Let the engine cool — never open the expansion tank cap while hot. Then check the level and the hoses.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.