Be sure that you've removed it completely. The current version of Covenant Eyes for Mac (2.8.3) leaves the following files:
- /Applications/Covenant Eyes.app
- /Applications/Utilities/Uninstall Covenant Eyes.app
Make sure you've removed ALL of them. The lists I've found for removal did not include the files at /Library/Extensions/Cvnt* which means that while it would ping, trace and respond to web services, it would still fail to connect to websites.
You'll need to unlock the kext files with the following before you can delete them:
chflags nouchg /Library/Extensions/Cvnt.kext
chflags nouchg /Library/Extensions/CvntDriver.kext
chflags nouchg /System/Library/Extensions/Cvnt.kext
chflags nouchg /System/Library/Extensions/CvntDriver.kext
After removing those files you may also have browser extensions installed that need to be removed through the browser itself.