Index: firmware/App/Modes/PreTreatmentRecirc.c
===================================================================
diff -u -r39156e21acec61d20fa49ee0adfffedf0f8597d9 -r75e1ae332d1446dddf9b8d4ce6e8317449c57d67
--- firmware/App/Modes/PreTreatmentRecirc.c	(.../PreTreatmentRecirc.c)	(revision 39156e21acec61d20fa49ee0adfffedf0f8597d9)
+++ firmware/App/Modes/PreTreatmentRecirc.c	(.../PreTreatmentRecirc.c)	(revision 75e1ae332d1446dddf9b8d4ce6e8317449c57d67)
@@ -7,8 +7,8 @@
 *
 * @file    PreTreatmentRecirc.c
 *
-* @author  (last)      Dara Navaei
-* @date    (last)      03-Nov-2022
+* @author  (last)      Michael Garthwaite
+* @date    (last)      19-Jan-2023
 *
 * @author  (original)  Quang Nguyen
 * @date    (original)  08-Feb-2021
@@ -22,6 +22,7 @@
 #include "DGInterface.h"
 #include "PreTreatmentRecirc.h"
 #include "Switches.h"
+#include "SystemCommMessages.h"
 #include "Timers.h"
 #include "Valves.h"
 
@@ -94,6 +95,8 @@
  *************************************************************************/
 void execPreTreatmentRecirc( void )
 {
+    HD_PRE_TREATMENT_RECIRC_STATE_T priorSubState = currentPreTreatmentRecircState;
+
     // Alarm if 2 hours recirculating
     if ( ( recircTOAlarmGiven != TRUE ) && ( TRUE == didTimeout( preTxRecircStartTime, WARNING_HIGH_PRIME_COMPLETED_TIME_MS ) ) )
     {
@@ -118,6 +121,10 @@
             break;
     }
 
+    if ( priorSubState != currentPreTreatmentRecircState )
+    {
+        SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_SUB_STATE_CHANGE, priorSubState, currentPreTreatmentRecircState );
+    }
     // All flags should be handled by now, reset in case flags not handle in current state
     resetPreTreatmentRecircFlags();
 }