SQL log indicates Logon failure, Error 18456, Severity: 14, State: 38....

Hi,

Just to be clear, I am not a SQL professional. I need to find out the root of this problem so i can contact whoever is responsible.
In the SQL log I discovered a logon error which occurs every 15min. In order to fix the issue I need to figure out what is triggering the logon. Which process/task is giving the errorError 18456, Severity: 14, State: 38

The error is so vague I don't know where to look. I only know something is using the Admin account to logon to some database which I do not see.

How do I trace where the logon is coming from?

Thanks in advance.