Do not driveTo the nearest safe stop
SPN 523470 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 and YaMZ, and what the second half of the code (FMI) means.
| FMI 0 | Rail pressure relief valve (PRV): open / spike / failed to open |
| FMI 1 | PRV: number of openings/opening time exceeds limit |
| FMI 2 | PRV: number of openings/opening time exceeds limit |
| FMI 4 | PRV: number of openings/opening time exceeds limit |
| FMI 7 | Rail pressure relief valve (PRV): open / spike / failed to open |
| FMI 11 | Rail pressure relief valve (PRV): open / spike / failed to open |
| FMI 0 | Fuel rail emergency valve stuck - Emergency valve opening detected. Blink code: 6-1-8. Power will be reduced. Repair: Check the pressure limiting valve and the fuel rail; replace the rail if necessary. |
| FMI 1 | Fuel rail emergency valve worn or stuck - Maximum number of emergency valve openings exceeded. Blink code: 6-2-2. Repair: Replace the fuel rail. Contact a service centre. |
| FMI 2 | Fuel rail emergency valve worn or stuck - Maximum emergency valve open time exceeded. Blink code: 6-2-2. Repair: Replace the fuel rail. Contact a service centre. |
| FMI 4 | Fuel rail emergency valve worn or stuck - Maximum number and duration of emergency valve openings exceeded. Blink code: 6-2-2. Repair: Replace the fuel rail. Contact a service centre. |
| FMI 7 | Fuel rail emergency valve stuck - Emergency valve failed to open when forced. Blink code: 6-1-8. Power will be reduced. Repair: Check the pressure limiting valve and the fuel rail; replace the rail if necessary. |
| FMI 11 | Fuel rail emergency valve stuck - Emergency valve forced open. Blink code: 6-1-8. Power will be reduced. Repair: Check the pressure limiting valve and the fuel rail; replace the rail if necessary. |
| FMI 0 | Fuel rail safety valve seized (Safety valve opening detected). Blink code: 6-1-8. Power will be reduced. Repair: Check the pressure limiting valve and the fuel rail; replace the rail if necessary. |
| FMI 1 | Fuel rail safety valve worn or seized (Maximum number of safety valve openings exceeded). Blink code: 6-2-2. Repair: Replace the fuel rail. Contact a service centre. |
| FMI 2 | Fuel rail safety valve worn or seized (Maximum safety valve open time exceeded). Blink code: 6-2-2. Repair: Replace the fuel rail. Contact a service centre. |
| FMI 4 | Fuel rail safety valve worn or seized (Maximum number and duration of safety valve openings exceeded). Blink code: 6-2-2. Repair: Replace the fuel rail. Contact a service centre. |
| FMI 7 | Fuel rail safety valve seized (Safety valve failed to open when forced). Blink code: 6-1-8. Power will be reduced. Repair: Check the pressure limiting valve and the fuel rail; replace the rail if necessary. |
| FMI 11 | Fuel rail safety valve seized (Forced safety valve opening). Blink code: 6-1-8. Power will be reduced. Repair: Check the pressure limiting valve and the fuel rail; replace the rail if necessary. |
Do not drive. Stop as soon as it’s safe to do so — don’t keep going.
The code is flagged critical: the manufacturer considers it unsafe to keep driving without checking.
This code alone cannot say what will fail next, so stop at the first safe opportunity and look at it on the spot.
That said, the manufacturer flags this code as critical — if in doubt, it is safer to stop and check on the spot.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.