Our recommendation is not to use the built-in ColdFusion probes. We suggest is creating a simple ColdFusion heartbeat template containing a very light database query. Locate this file in a directory outside of any main web application roots to avoid invoking any of your main application code.
Here is a simple example:
<cfquery name="heartbeat" datasource="DSN">
Select probe from masterDB where active = 1
<!--- Capture errors here --->
Here are the default settings for System Probes.