Question: Multiple questions on meta indicate, that code-only answers, if they are self-explanatory and, what's more important, correct, do not fall into *low quality*: [1](https://meta.stackoverflow.com/questions/303772/failed-audit-when-commenting-on-code-only-answer), [2](https://meta.stackoverflow.com/a/258676/7606764).

Meanwhile I failed the audit when I accepted a code-only answer:

[![enter image description here](https://i.stack.imgur.com/5mIm3.png)](https://i.stack.imgur.com/5mIm3.png)

What is wrong with that?

Edit: I think this question is more specific, than duplicate candidate as it limits itself to code-only answers.

Answer: 
> 
> *"if they are self-explanatory"*.
> 
> 
> 

That answer is not self-explanatory.

It's a code dump where the OP has to figure out what changed, and more importantly: *why*. It doesn't explain why the changes make the code work.

Answers like that *are* of low quality. Maybe not enough to flag or delete them, but they definitely don't look "Ok". (I usually downvote cases like that)

When in doubt, `Skip` the review.
The failure here seems to be due to two misconceptions:

1. That your only options on the first post queue are, No action
needed, Edit, Flag and Skip. 

In actuality, there are several other options including upvote, downvote, and commenting. These options are conspicuously present in this queue as opposed to others like triage.
2. That the first post queue is just for checking for correctness, like triage or low quality queue. 

Like Servy pointed out in the comments, action is expected as part of this queue even if the answer is not bad enough to flag. The bar is higher than triage. The whole point of it is to help others improve the quality of their posts.

In summary, I think the correct actions would have been: 

* Edit: If you know about the technology, you could edit the answer yourself to provide context.
* Comment: If you don't know about the technology, you can comment and ask OP to provide context
* Downvote: You can downvote if you're inclined.
* Skip: You can skip if you're not inclined, or not sure.