Bizhub c300i not printing Y on Gradation

[Esron Thomas]

Hi guys I am working on a bh c300i that customer request due to an error message "An internal error has occurred. Error will be cleared automatically. " I login to the CE mode checked service call history and found trouble code c2551. checked state confirmation, confirmed tcr y 15.0%, tried to print the Gradation halftone but start grayed out. End the CE mode, print Demo page, printed but not yellow present. i login to CE mode try stabilized machine, try print gradation halftone the pages came out blank nothing on the 10 copies printed.
Thank you for any ideas.

[Black Cloud]

C2551 is a cyan toner density low. Not related to yellow. The first thing I would do is look at the yellow mag roller on the developer unit. Is there developer?

[kingarthur]

15% for yellow is about 2.5 times what it should be, ideally should be about 6%, but like Black Cloud says, C2551 is low cyan density. When you go into service mode initially do you have the "triangle" at the top of the screen, if so, what are the P codes