Code 14091: [Channel %1: ] Block %2 illegal function, index %3
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Block %2 illegal function, index %3 alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Parameters: %1 = Channel number %2 = Block number, label %3 = Index Definitions: A function was programmed or triggered which is not allowed in the current program context. The code of the function in question is encoded in the "index" parameter: Index == 1: "RET" command was programmed in the main program level Index == 2: Conflict between "Cancel level"/" Clear number of passes" and "Implicit GET" Index == 3: Conflict ASUB start immediately after selection of overstore (up to P3) Index == 4: MD10760 $MN_G53_TOOLCORR = 1: SUPA/G153/G53 programmed in G75 Index == 5: POSRANGE command not programmed in synchronized action Index == 6: SIRELAY command not programmed in synchronized action Index == 7: GOTOF/GOTOB/GOTO command progra mmed with string variable in synchronized action. Index == 8: COA application "cutting generator" not active Reaction: Interpreter stop NC Start disable in this channel. Interface signals are set. Alarm display. Remedy: Index == 1: Substitute "RET" command with M17/M30 Index == 2: Insert an auxiliary block (e.g. M99) after the subroutine call to which the "Cancel level"/"Clear number of passes" refers Index == 3: Overstore an auxiliary block (e.g. M99), then start ASUB (up to P3) Index == 4: With MD10760 $MN_G53_TOOLCORR = 1: Do not activate SUPA/G53/G153 in the G75 block Index == 5: Program POSRANGE command in synchronized action Index == 6: Program SIRELAY command in synchronized action Index == 7: Program GOTOF/GOTOB/GOTO command with block number or label Index == 8: Load COA application "cutting generator" Program Continuation: Clear alarm with the RESET key. Restart part program
Source: SINUMERIK 840D sl / 840Di sl / SINAMICS S120 Diagnostics Manual (DAsl, 03/2009)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Siemens SINUMERIK 840D CNC Alarms
Siemens controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 14091 on the SINUMERIK 840D CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Siemens's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4014 Siemens SINUMERIK 840D CNC codes.
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