Safe to driveDrivable, but watch it yourself
SPN 520193 is a manufacturer number outside the standard J1939 table: different makes can put different things under it. Below — how it is worded by KAMAZ, MAZ, Volvo and YaMZ, and what the second half of the code (FMI) means.
| FMI 3 | Air flow sensor: sensitivity deviation |
| FMI 4 | Air flow sensor: sensitivity deviation |
| FMI 3 | Mass air flow sensor reading error - Air flow above allowed. Blink code: 2-3-4. Repair: Check the mass air flow sensor and its wiring. |
| FMI 4 | Mass air flow sensor reading error - Air flow below allowed. Blink code: 2-3-4. Repair: Check the mass air flow sensor and its wiring. |
| FMI 5 | LCM output current to the lamp is below 0.1 A. Open supply wire between the LCM and the lamp, open wire between the lamp and the ground point, or lamp failure. |
| FMI 6 | LCM output current to the lamp is above 3.1 A. Wire shorted to ground between the LCM and the lamp. Possibly several lamps are connected, or a higher-wattage lamp is installed. |
| FMI 3 | Mass air flow sensor reading fault (Air flow above allowable limit). Blink code: 2-3-4. Repair: Check the mass air flow sensor and its wiring. |
| FMI 4 | Mass air flow sensor reading fault (Air flow below allowable limit). Blink code: 2-3-4. Repair: Check the mass air flow sensor and its wiring. |
Safe to drive. Below — how much time you have and what happens if you keep going.
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.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.