Look at this post
This worked for me:
Go to your google accounts by logging in to http://accounts.google.com/
In the ‘Security’ menu (left side of the window), go to the 2-step verification section
Under this section.,
click the ‘Manage your application-specific passwords’ link.
Sign-in again (if prompted)
Set any name relevant to the application. For example, pidgin-messenger and hit the ‘Generate Password’ button.
Copy the password generated (along with the spaces, it doesn’t matter) and hit the ‘done’ button.
Now, hit the ‘Modify account’ button on the Pidgin window, paste the copied password in the ‘password’ text box and click the ‘save’ button. You will again be presented the ‘Add accounts’ window. In this window try again to tick the ‘Enabled’ check box