Can anyone tell me what this is? What causes it? What happens? Got a call out to work on a duplex pair. They claimed they both would not reset. Faults listed 401. 402. On both controllers.

401 subsysstart. 0x000008 on car 1
401 subsysstart. 0x000007 on car 2

402 subsysdead. 0x000008 on car 1
402 subsysdead. 0x000007 on car 2

Reset. Hard reset. Inspection reset. Clear faults.

Car 2 repopulating it's 402 fault. Any ideas?