Safe to driveUntil the next service
SPN 520399 is a manufacturer number outside the standard J1939 table: different makes can put different things under it. Below — how it is worded by SITRAK and Volvo, and what the second half of the code (FMI) means.
| FMI 2 | SMU hardware monitoring module: alarm group 6, failure 7. Scan tool code: P3144. Effect: Torque limited, the engine may shut down. |
| FMI 12 | LCM (MID216) is not receiving signals from the gear shift selector control unit (MID223) over the SAE J1587 data link. Open or partially damaged data link wiring between the units. |
| SPN 520399 FMI 2520399/2 · 520399.2 | data erratic or intermittent |
| SPN 520399 FMI 12520399/12 · 520399.12 | faulty device or component |
Safe to drive. Below — how much time you have and what happens if you keep going.
A standalone fault with no immediate consequences for driving.
Show the codes at the next service. If a second code from the same system appears, stop putting it off.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.