Haas CNC controls are a little different from Fanuc, Mitsubishi or Siemens: every alarm is shown on screen with a number and a descriptive message, so you usually know the affected subsystem at a glance. This guide covers the alarms Haas technicians meet most often, with causes and fixes.
How Haas Alarms Work
On both the classic Haas control and the newer NGC (Next Generation Control), alarms appear on the ALARMS screen with a code and plain-English text. They broadly fall into these groups:
- Servo / axis — following error, overcurrent, overload, encoder
- Spindle / vector drive — drive faults, overheat, gear change
- Air & lubrication — low air pressure, low lube
- Power — low/high voltage, regen, overheat
- Communication / processor — MOCON / Maincon and bus faults
Common Haas Alarms
| Alarm | Meaning | Common Cause & Fix |
|---|---|---|
| 102 | Servo Error Too Large | Axis following error exceeded the limit — mechanical bind, way-lube issue, faulty servo/drive, motor or encoder. Check for binding and inspect the axis amplifier. |
| 107 | Emergency Off (E-Stop) | The E-stop button is pressed or its circuit is open. Release the button and check the E-stop chain/wiring. |
| 111 | Low Air Pressure | Shop air below the required pressure. Check the supply, regulator and for leaks (needs ~85+ psi typical). |
| 112 | No Reference Point / Z Home | Machine not homed. Perform Power-Up/Restart (zero return); check the home switch if it fails. |
| 117 | Spindle Gear Change Fault | Gearbox did not shift (gear-driven machines). Check the shift solenoid/air and the gear-position switches. |
| 119 | Regen / Overheat | Regenerative load or cabinet overheat. Check the regen resistor, cabinet cooling and ambient temperature. |
| 120 | Low Voltage | Incoming line voltage too low or unstable. Verify the 3-phase supply and transformer tap settings. |
| Low Lubrication | Way/axis lube low or no pressure | Refill the lube reservoir; check the lube pump, lines and pressure switch. |
| Spindle Drive Fault | Vector drive / spindle amplifier fault | Read the on-screen detail — check spindle motor, drive cooling, DC bus and load. Repair/replace the vector drive if faulty. |
| MOCON / Maincon error | Motor controller / main processor fault | Communication or processor board fault. Re-seat boards and cables; a faulty Maincon or MOCON board may need repair or replacement. |
First Steps When a Haas Alarms
- Read the full on-screen alarm text — Haas usually names the exact subsystem and axis.
- Clear simple conditions first (E-stop, low air, low lube, not homed) and press RESET.
- For servo/spindle faults, check for mechanical bind, then inspect the drive, motor and encoder.
- For repeated processor/communication alarms, re-seat the Maincon/MOCON boards and ribbon cables.
Need the Part — or a Repair?
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Quick-reference of common alarms. Haas alarm numbers can vary between the classic and NGC controls — always read the on-screen text and refer to your Haas Operator's Manual alarm list for the exact code.