CertificateServicesClient-CertEnroll error 13 and CertificateServicesClient-AutoEnrollment error 6 repeats every 5 minutes

Caused by a Certificate Authority (CA) removed from the domain. In this case it was an Exchange 2010 server. The uninstall did not remove some CA references which caused the errors whenever it tried to communicate with it.

You have to go into AD Sites and Services and remove several entries listed in the link.

Sources

• http://www.petenetlive.com/KB/Article/0000473.htm