Why is my picture colour faint when printing

The CISS printers are a bit tricker to nail it down on by design. First thing I would do before you go further as this generation is notorious for filling the waste ink pad up with how frequently these early Canon CISS printers "self cleaned" is run a full color page like this on best, or do it 3-4 times. If it's an air issue, that will get ink back in the lines with less waste ink use.

If the page does not help, remove and soak the "cartridges" that Canon considers printheads in hot water. Use this guide for the cleaning steps: HP/Canon - Printhead cleaning -- ink tank/printhead permanently installed (modular) -- if it continues, the printheads are like $25-30 so Canon priced them to be worth doing if the newer generation with the modular waste box is not on sale. If you only need to replace one, it's worth doing - both can get dicey depending on what sales the stores run when they use printers as a loss leader to get you in the store. Do a quick printhead clean to get ink back in the system if the nozzle check is spotty.

If neither helps, run a 2nd printhead clean - DO NOT POWER CLEAN THESE UNLESS YOU WANT TO KILL IT WITH A 5B ERROR! They're at the age 5B00/5B02 errorss are happening in mass with the deep clean. If it continues, let it sit for 24 hours and try the standard clean again.

The lowest end Canon sold with the maintenance cartridge is the MegaTank PIXMA G329 (MC-G07) if the printer is bad, you do run the deep clean and get a 5B error.

Generally due to ink, a blocked nozzle or incorrect settings. Run through a nozzle check/head clean and select photo paper & high quality.