Thank you for using the Support Forum. Please try these steps to default the printer to Black and White.
1. In the Embedded Web Server, log in as administrator, then click System→Defaults and Policies.
2. In the Common area, click Color Printing Optimization.
3. Select the black & white option, then click OK
If this does not help, please consider contacting your support centre for further assistance.
We are out of Cyan toner, but I just want to print in black and white. Can I force the C405 to print in B&W without replacing the Cyan toner?