04-05-2016 09:59 AM
Welcome to the Canon Community and thank you for your post!
So that the Community can help you better, we will need to know about any error messages you're seeing, and the version of OS X you're using, as well as the way you connect to your printer (USB or networked via WiFi or Ethernet). It's also helpful to know what software you use to scan.
Any other details you'd like to give will only help the Community better understand your issue!
If this is an urgent support need, please CLICK HERE to reach our friendly Technical Support Team by phone or email.
Thanks and have a great day!
04-07-2016 09:29 AM
Try installing our latest drivers and MP Navigator program from our website. Visit www.usa.canon.com and search for your MX340 to access the downloads. The MP Navigator is the program we recommend for scanning.
If the scanning issue persists once this has been done, find more help at Contact Us.