Siemens SINUMERIK codes
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Siemens SINUMERIK Controller

Program/G-code · Intermediate · 30-120 minutes

Alarm 120021

Siemens 840D 120021 - PCU fan monitoring housing fan 1

Siemens SINUMERIK message 120021: PCU fan monitoring housing fan 1. This is an operator information message from the SINUMERIK control. Note the complete message text as it may contain important parameter values.

Siemens SINUMERIKProgram/G-codeIntermediate30-120 minutes

120021

Siemens 840D 120021 - PCU fan monitoring housing fan 1

PCU fan monitoring housing fan 1

Siemens SINUMERIK message 120021: PCU fan monitoring housing fan 1. This is an operator information message from the SINUMERIK control. Note the complete message text as it may contain important parameter values.

Safety

  • Refer to Siemens documentation
  • Ensure qualified technician performs repairs

Common Causes

  • Normal control operation generated this status message
  • User action or program command triggered this notification
  • System configuration or commissioning activity produced this message
  • Machine data or parameter change created this notification

Troubleshooting Steps

  1. 1Read the complete message text on the SINUMERIK screen — note any parameter values shown.
  2. 2If action is required, follow the instructions in the message.
  3. 3Acknowledge the message on the operator panel to continue operation.
  4. 4Consult the Siemens SINUMERIK alarm documentation for message 120021 if clarification is needed.
  5. 5If this message appears unexpectedly, review recent parameter or configuration changes.

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