Cause of error code U163

See below

Solution for error code U163

Your machine is prompting you to replace empty cartridges. If this message is displayed after inserting a new ink cartridge, you can remove this error code by carrying out the following instruction. On your Canon printer, find, press and hold down the STOP/RESET/RESUME button for 10 seconds. This lets the printer know you're aware of the message but wish to continue printing anyway. You will be allowed to print as normal.