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ErrorLib — Industrial Fault Code Library

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231-A094

Drive lock of spindle, tool holder opened

Heidenhain · TNC CNC Controllers

What does 231-A094 mean?

This error indicates that a spindle drive was locked. This occurs when an attempt was made to switch on a spindle drive while the guard door was open AND the tool holder was also open, or due to an internal software error.

Common Causes

  • Attempt to switch on a spindle drive while the guard door was open and the tool holder was open.
  • Incorrect status reading from the guard door or tool holder sensors.
  • Internal software error.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Ensure the guard door is securely closed and locked.

  2. 2

    Confirm that the tool holder is fully closed and locked.

  3. 3

    Check the wiring and functionality of both the guard door sensor and the tool holder sensor for proper operation.

  4. 4

    Verify the software version of the controller and update it if a known issue related to spindle interlocks exists.

Browse all codes in this manual (47)
Verified technical data. Last updated: April 2026

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Source: Heidenhain TNC CNC Controllers
Open Manual (Page 466)Search more codes in this manual