My Konica Biz C451 starts print in color with full 100% Magenta.

SOURCE: prints black on test page, but not when a job is sent to the printer

I just posted and also fixed my problem. Try "deep cleaning" under the maintenance tab. Choose the black cartridge only. Mine only took once to fix but i'd try it 1-3 times before giving up on this solution. It now prints the test page with black and color

SOURCE: Brother DCP 130C not printing magenta and yellow

after replacing the ink cartridges it took several cleans to come good. I have no idea how to "manually" clean the heads. So I told the printer to do it many (about 7) times. It eventually worked

SOURCE: Print Booklets with Konica Minolta Biz Hub C650 Printer

Select Print, and then "Properties"

Layout Tab - select Print Type: Booklet

Basic Tab - Select original size and then size of PAPER to be printed. 11x17 is standard 8.5x11 book when folded.

Finish Tab - select saddle stitch.

Thats it, easy as pie.

SOURCE: Konica Minolta BizHub C451 printing red lines down documents

your imaging unit is damaged. call minolta guys to have a look it at and change it if neccessary

SOURCE: Canon Pixma yellow color problem

Either the ink you are using is not going to give the color you want, or you have print heads that are blocked.