To fix the B200 error on a Canon MG5150 printer please see the guide below.
1. Turn off the main power
2. Open the door to access the print head (the same door you use to change the inks)
3. Turn on the main power
4. Wait for print carriage assembly to start moving to the left and let it go past half way
5. Before print carriage reaches left hand side (but after going halfway across) shut the cover.
6. Leave the printer power turned on
7. All going to plan your printer should be happy and error free. If not repeat the procedure and keep an eye out for any obstructions in the carriage assemble path.
We have tested this on the MG-5150 printer but it may well work on others from the same range.