Thanks. See, this problem can happen due to three reasons, if there is any paper jam in real, if the cartridges are jammed or if the sensor is defective. As you have removed the jammed paper from the printer and the cartridges can move freely, it means the problem is with the sensor. This is not a rear problem, specially with Canon printers. It seems the sensor was damaged due to the paper jam and that is why the printer is still showing the error instead of removing the jammed paper from the printer.
This problem can be repaired at home with the help of a service manual, but the main problem is that , you will not get a replacement sensor in any shop, as they are only available in repair shops and they do not sell it separately. So, the final solution for this problem is repairing the printer.
But, honestly speaking, if the printer is more than 3 years old then, I will recommend you to replace the printer. Now, you have to decide, what you want to do,let me know if you want any further information, otherwise please rememeber to give postive rating below, as that is the only way I am compensated for my time and effort.