Troubleshooting The SENSEO CALC light lights up red It indicates that you have to descale the SENSEO. solution: The CALC light lights up red continuously after you have brewed approx. 400 cups of coffee. In the attachment below you can find the PDF file with instructions on how to descale your SENSEO Viva Café. Section Attachment PDF file, published 2018-06-20 After descaling, the CALC light is still on: Make sure you do not switch the machine off during the descaling process. If so, you will have to restart the descaling procedure again and make sure that you execute the right steps in order to get the CALC LED to switch off.