[CentOS] e2fsck but says mounted and cannot

Wed Feb 24 19:02:38 UTC 2021
Jerry Geis <jerry.geis at gmail.com>

I have a system that needs to run e2fsck (C7). I boot into rescue mode,
skip to shell (option 3).
enter they PW and I type:

e2fsck -y /dev/sda1
and it says is mounted. This is "/"

What do I do so I can run e2fsck ?