Some time ago I faced the this situation in a client. SYSAUX was simply growing with no reason, but retention and everything has not changed.
After some research, could map issue to Bug 14084247: STBH: ORA-01555 DUE TO WRH$_ACTIVE_SESSION_HISTORY NOT PURGED.
There is an one-ooff patch, but needs also extra steps to make it work, as stated on MOS: Excessive AWR Growth From Partitioned Objects Such as SYS.WRH$_EVENT_HISTOGRAM Causing Sysaux to Grow (Doc ID 1912201.1):
However, even after applying bug patch 14084247, this fix will not have an immediate effect and may take some time to "catch up".
The good new is that this can also be applied in on-line patching mode. I did another post documenting this patch applying: Online Data Patch Apply with multiple Databases on same Oracle Home: OPatch failed with error code 26
Some other relevant MOS Documents under this subject are:
– WRH$_ACTIVE_SESSION_HISTORY Does Not Get Purged Based Upon the Retention Policy (Doc ID 387914.1)
– Suggestions if Your SYSAUX Tablespace Grows Rapidly or Too Large (Doc ID 1292724.1)
Ok, but waht can I do right now?
You can purge the top AWR tables, as described on MOS: WRH$_LATCH, WRH$_SYSSTAT, and WRH$_PARAMETER Consume the Majority of Space within SYSAUX (Doc ID 2099998.1).
Check steps below on how it can be done: