Gail in answer to the following:
Check that it's scheduled, check that the settings are correct, check that it's actually running.
The job is scheduled and the job is enabled - the job says it ran when I look in the history. There is a green tick next to the job and i have the following message:
Executed as user: MydomainXXX\ServiceAccount. Microsoft (R) SQL Server Execute Package Utility Version 10.50.2500.0 for 64-bit Copyright (C) Microsoft Corporation 2010. All rights reserved. Started: 23:30:00 DTExec: The package execution returned DTSER_SUCCESS (0). Started: 23:30:00 Finished: 23:31:17 Elapsed: 76.437 seconds. The package executed successfully. The step succeeded
Yet there is no message in the sql error log to say that a dbcc checkdb command ran on the system databases or another databases for that matter. If I manually run the dbcc checkdb against each system db then I get a successful entry in the error log and my sql monitor reports back the 'database integrity check overdue' error has now ended.