Why did you receive this error on Google+?:

"Access Limited

You've recently been violating the Google+ User Content and Conduct policies.Comments that contain spam, such as unwanted promotional or commercial content, or unwanted or mass solicitations, are not allowed on Google+. Offensive, off-topic, or repetitive comments are not allowed either.Because we've warned you about violating our policies before, you will have only limited access to Google+ for two weeks. During this time, you will not be able to use most features of Google+, such as sharing posts or making comments. Learn moreWhile you have limited access to Google+, you can still use other Google products and services, such as Gmail, though some of their social features may be limited. Please review our policies to avoid violating them in the future. Learn more If you continue to violate our policies, your access to Google+ and other features and services that require an active Google+ profile may be suspended permanently. Learn more We understand that Google+ and its policies may not be for everyone. If you do choose to leave, you can make a copy of your Google+ data. If you like, you can also disable Google+ entirely."

When you're account access is limited you won't be able to comment anymore either. If you try to comment you will see this error "There was a problem updating your comment. Please try again.".

Google won't tell you why you were banned

You can't know for sure. You can click on the 'User Content and Conduct' and see a list of possible reasons why you've been temporarily banned, but you would only be guessing what the cause is.

The real mechanics behind Google+ ban policy

The real reason you were banned on Google+  is because other people on Google+ reported you or flagged you. Google's current Google+ banning system is designed around majority rules. It is designed to eliminate those who annoy the majority. If your comments are nonconformist, or unconventional, you will get flagged and banned from Google+. There's no one you can contact at Google to resolve this. There's no contest page...

I've tested this using up 2 of my verification phone numbers in the process. I simply found controversial subjects like abortion, taboos, and freedom of religion and used a counter viewpoint to the posters. I was not inflammatory in any way, even though the posts were always usually inflammatory.  I made  about 20-30 posts, each with unique content ranging from 1-3 paragraphs sometimes including links to a research paper I sited.  I got banned the next day. I repeated the process on two accounts, so I know this is how Google's Google+ system works contrary to what Google implies on their User Content and Conduct page.

A lot of people say that Google+ is better than Facebook, but based on this mob mentality majority rule flagging system, I don't think Google+ is any better than Facebook.