What causes FANUC alarm 248?

Part program contains an illegal G-code or M-code combination for this alarm type. Missing or incorrect address word in the program block. Axis or parameter value out of range for the commanded function. Required option not enabled on this CNC for the commanded function. Conflict between active modal states and the commanded function.

How do I fix FANUC alarm 248?

1. Note the block number shown on the alarm screen and locate that block in the program. 2. Review the command in that block against the Fanuc programming manual for alarm 248. 3. Check for missing address words, incorrect values, or conflicting G-code combinations. 4. Verify any required CNC options are enabled if using advanced functions. 5. Correct the program and verify the fix before restarting machining.

axismd.ai

FANUC Controller

Program/G-code · Intermediate · 5-30 minutes

Alarm 248

Fanuc 248 - Illegal axis name

Alarm 248 occurs when the control encounters an axis designation that is not recognized or not configured in the system parameters. This typically happens when a part program references an axis name that doesn't exist in the machine configuration, uses incorrect syntax for axis naming, or attempts to command a rotary/additional axis that isn't physically present or enabled.

FANUCProgram/G-codeIntermediate5-30 minutes

248

Fanuc 248 - Illegal axis name

ILLEGAL AXIS NAME

Root Cause Summary

Alarm 248 occurs when the control encounters an axis designation that is not recognized or not configured in the system parameters. This typically happens when a part program references an axis name that doesn't exist in the machine configuration, uses incorrect syntax for axis naming, or attempts to command a rotary/additional axis that isn't physically present or enabled.

Safety

Verify corrected program or parameters before resuming machining

Causes and Fixes

1
Review the active G-code line displaying the alarm and identify which axis letter is being called (e.g., G01 X10 Y20 B45).
2
Access parameter settings and verify parameter 1020 (number of controlled axes) to confirm how many axes are configured in the system.
3
Check parameters 1021-1030 to verify which axis names are assigned to each controlled axis number. Ensure the axis referenced in the program matches the configured names.
Do not modify axis parameters without recording original values and understanding machine kinematics.
4
If the axis is not needed, edit the program to remove references to that axis. If the axis should exist, contact your machine tool builder to properly configure the additional axis parameters.

Service Recommended confidence

Seeing Multiple Alarms?

Seeing another alarm with this one? Enter the code.

Get machine-aware diagnosis

AxisMD logs alarms against your actual machines, tracks patterns, and gives AI context your manual doesn't have.

Start free

Was this guide helpful?

Always verify with your machine manual or a certified technician before performing service procedures.