Safe to driveEnough to reach the yard
J1939 code SPN 730. Below — how the fault is worded at the factory by KAMAZ, MAZ, Renault Trucks and YaMZ, and what the second half of the code (FMI) means in the standard.
| FMI 3 | Air heater shutoff monitoring. K-line code on KamAZ-5490: ADM3 13903. |
| FMI 4 | Air heater shutoff monitoring. K-line code on KamAZ-5490: ADM3 13904. |
| FMI 1 | Intake air pre-heater 2 driver circuit fault - Short to battery positive. Blink code: 3-2-1. Repair: Check the air preheater and its wiring. |
| FMI 2 | Intake air pre-heater 2 driver circuit fault - Overheating. Blink code: 3-2-1. Repair: Check the air preheater and its wiring. |
| FMI 3 | Intake air heater 2 test error - Voltage drop above the maximum allowed. Blink code: 3-2-3. Repair: Check the air preheater and its wiring. |
| FMI 4 | Intake air pre-heater 2 driver circuit fault - Open circuit. Blink code: 3-2-1. Repair: Check the air preheater and its wiring. |
| FMI 8 | Intake air pre-heater 2 driver circuit fault - Short to ground. Blink code: 3-2-1. Repair: Check the air preheater and its wiring. |
| FMI 11 | Preheating runs continuously — risk of fire. Repair: Check the continuity and insulation of the wiring (SL2/9), check relays R15 and R16. |
| FMI 1 | Intake air preheater driver circuit 2 fault (Short to battery positive). Blink code: 3-2-1. Repair: Check the air preheater and its wiring. |
| FMI 2 | Intake air preheater driver circuit 2 fault (Overheating). Blink code: 3-2-1. Repair: Check the air preheater and its wiring. |
| FMI 3 | Air preheater 2 test fault (Voltage drop above maximum allowable limit). Blink code: 3-2-3. Repair: Check the air preheater and its wiring. |
| FMI 4 | Intake air preheater driver circuit 2 fault (Open circuit). Blink code: 3-2-1. Repair: Check the air preheater and its wiring. |
| FMI 8 | Intake air preheater driver circuit 2 fault (Short to ground). Blink code: 3-2-1. Repair: Check the air preheater and its wiring. |
Safe to drive. Below — how much time you have and what happens if you keep going.
Boost is not reaching its target: turbo, intercooler or intake. The engine compensates with mixture and runs hotter than usual.
You will lose pull, burn more fuel and add overheating on long climbs. If you hear a whine or a whistle from the turbo, stop — the wheel is breaking up.
This is an electrical fault: an open, a short or a bad contact in the sensor circuit. The value it measures is most likely fine. You can drive. But until the circuit is repaired this system runs blind and cannot warn you about a real failure.
That said, the manufacturer flags this code as critical — if in doubt, it is safer to stop and check on the spot.
Inspect the air filter and charge-air hoses: leaks and cracks produce exactly these codes.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.