Safe to driveDrivable, but watch it yourself
SPN 520200 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 20 | Service signal: cylinder compression test |
| FMI 20 | Cylinder compression test in progress - Test in progress. Blink code: 5-2-1. |
| FMI 5 | LCM output current to the lamps is below 500 mA. Open wires between the LCM and the lamps, open wire between the lamp and the ground point, or lamp failure. |
| FMI 6 | LCM output current to the lamps is above 2.25 A. Wire shorted to ground between the LCM and the lamps. Possibly several additional lamps are connected, or higher-wattage lamps are installed. |
| FMI 20 | Engine cylinder compression test in progress (Test running). Blink code: 5-2-1. |
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.