Do not driveMinutes
J1939 code SPN 973. Below — how the fault is worded at the factory by International and Mercedes-Benz, and what the second half of the code (FMI) means in the standard.
| FMI 2 | Engine Retarder Selection — Engine Retarder Level Selection Switch Error |
| FMI 2 | Evobus 5stage retarder level position not plausible |
| FMI 9 | J1939 EBC1 Message is missing or not available |
| SPN 973 FMI 2973/2 · 973.2 | data erratic or intermittent |
| SPN 973 FMI 9973/9 · 973.9 | abnormal update rate |
Do not drive. Stop as soon as it’s safe to do so — don’t keep going.
Part of the brake circuit or ABS/EBS is out of service. The pedal may still feel normal — until the first emergency stop or descent.
Next comes longer stopping distance, a skid on a slick surface, failure on a long downgrade. This is the case where "I will take it slow" does not work.
Let the air system build to working pressure and listen for leaks. Don’t drive with faulty brakes.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.