Siemens alarm 431003: General error in the F program
SINUMERIK PLC system alarm · Siemens 840D/810D powerline
What it means
The fail-safe runtime detected a serious problem while executing in safety mode; the generic text hides details that only the STEP 7 F-diagnostics can reveal. Because an uncontrolled condition inside the F program is safety-relevant, the machine must come out of operation until the cause is analysed. Connect STEP 7 and evaluate the F diagnostic buffer as prescribed by Siemens.
Likely causes
- Runtime/compile inconsistency in the F user program
- Incompatible F block versions after project changes
- Corrupted F program sections in load memory
Triage note: Exact analysis requires STEP 7; treat together with 430000-430010 F-system alarms.
Need the part urgently?
Send us alarm 431003 with your machine details — typical RFQ turnaround is 24–48h.