Safe to driveDrivable, but watch it yourself
SPN 520203 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, SITRAK, Volvo and YaMZ, and what the second half of the code (FMI) means.
| FMI 3 | Cab air temperature sensor |
| FMI 4 | Cab air temperature sensor |
| FMI 3 | Ambient air temperature sensor error - Voltage above allowed. Blink code: 6-2-1. Repair: Check the ambient air temperature sensor and its wiring. |
| FMI 4 | Ambient air temperature sensor error - Voltage below allowed. Blink code: 6-2-1. Repair: Check the ambient air temperature sensor and its wiring. |
| FMI 2 | The engine stop button has been held for too long. Scan tool code: P2536. Effect: Loss of communication with the modules, some functions are disabled. |
| FMI 5 | The engine compartment start button has been held for too long. Scan tool code: P2536. Effect: The engine will not start. |
| FMI 14 | Implausible engine compartment start button signal on the CAN bus. Scan tool code: P2536. Effect: Loss of communication with the modules, some functions are disabled. |
| FMI 19 | Implausible engine compartment stop button signal on the CAN bus. Scan tool code: P2533. Effect: Loss of communication with the modules, some functions are disabled. |
| 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 1.8 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 | Ambient air temperature sensor fault (Voltage above allowable limit). Blink code: 6-2-1. Repair: Check the ambient air temperature sensor and its wiring. |
| FMI 4 | Ambient air temperature sensor fault (Voltage below allowable limit). Blink code: 6-2-1. Repair: Check the ambient air temperature 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.