Where is my 404 error log file in WordPress?

Here is a weird one. CentOS Linux install

When I have a 404 error on my site it gets redirected to my 404.php on my theme page. Nice.

When I am on the hunt for problems I usually head over to /var/log/httpd/websitename-error.log and look for file not founds.

BUT these errors are not logged (there) where do I find the log file for the 404 errors?