An outage has happened in our agent machine on patching SSL which was unsuccessful and rolled back, from then job failed with Exit code:13.
By looking into the joblog of this specific job (located in the spool directory of the System agent), found out that exit code 13 was due to a permission error on the std_out_file.
The owner of the Oracle job was: guest
The owner of the std_err_file was "guest" but it was "autosys" for the std_out_file
System Agent 11.3 SP6 on Linux but it might happen with any other service pack
Changed the owner of the std_out_file of this std_out_file to "guest" instead of "autosys"