What causes FANUC alarm 004?

Part program contains an illegal or malformed command related to the alarm condition. Missing required address word or parameter value in the program block. Programmed value is out of the allowable range. Conflict between active modal codes and the commanded function. Post-processor configuration mismatch for this Fanuc series.

How do I fix FANUC alarm 004?

1. Note the block number shown in the alarm screen and locate that block in the program. 2. Review the command in that block against the Fanuc programming manual. 3. Check for missing words, incorrect values, or conflicting G-code combinations. 4. Verify the program is post-processed for the correct Fanuc series. 5. Correct the program and dry-run at low speed before resuming machining.

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FANUC Controller

Program/G-code · Basic · 5-15 minutes

Alarm 004

Fanuc Alarm 004 - First Address Error

Fanuc Alarm 004 occurs when the CNC controller encounters a program block that does not begin with a valid address letter (G, M, X, Y, Z, etc.) or starts with an invalid character. This is typically caused by incorrect program formatting, special characters in the first position, or data corruption during program transfer or editing.

FANUCProgram/G-codeBasic5-15 minutes

004

Fanuc Alarm 004 - First Address Error

Address Not Found

Root Cause Summary

Fanuc Alarm 004 occurs when the CNC controller encounters a program block that does not begin with a valid address letter (G, M, X, Y, Z, etc.) or starts with an invalid character. This is typically caused by incorrect program formatting, special characters in the first position, or data corruption during program transfer or editing.

Safety

Program will not run

Causes and Fixes

1
Press RESET to clear the alarm, then press PRGRM key and navigate to the program causing the error. Note the program number and sequence number displayed with the alarm.
2
Use cursor keys to locate the exact block referenced in the alarm. Check if the block starts with a space, number without address letter, or non-alphanumeric character instead of valid addresses (G, M, X, Y, Z, A, B, C, I, J, K, F, S, T, H, D, N, O, P, Q, R, U, V, W).
3
Correct the block by removing invalid leading characters or adding the proper address letter. Ensure EOB (End of Block) semicolons or LF characters properly separate blocks.
4
If editing on the CNC, verify Parameter 3202 (Edit Lock) bits allow program modification. Test the corrected program in single block mode (SINGLE BLOCK button ON) to verify proper execution.
Always backup programs before editing using SYSTEM > Program > File > Output or DNC transfer

DIY Feasiblehigh confidence

Call a technician if:

·Persistent alarm after program correction
·Parameter corruption suspected
·Hardware communication issues

Prevention

Use proven CAM post-processors
Validate programs in simulation before transfer
Maintain consistent I/O parameter settings
Regular backup of working programs

Common Mistakes

Editing programs while in AUTO mode
Ignoring cursor position in alarm message
Assuming all macro variables are enabled by default
Not checking parameter settings after control updates

Related Alarms

003 005 010 078

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