Index: firmware/App/Modes/ModePostTreat.c
===================================================================
diff -u -r43d1739837a207e6d4d2960f3f0442af85b22a8c -r75e1ae332d1446dddf9b8d4ce6e8317449c57d67
--- firmware/App/Modes/ModePostTreat.c	(.../ModePostTreat.c)	(revision 43d1739837a207e6d4d2960f3f0442af85b22a8c)
+++ firmware/App/Modes/ModePostTreat.c	(.../ModePostTreat.c)	(revision 75e1ae332d1446dddf9b8d4ce6e8317449c57d67)
@@ -7,8 +7,8 @@
 *
 * @file    ModePostTreat.c
 *
-* @author  (last)      Sean Nash
-* @date    (last)      04-Jan-2023
+* @author  (last)      Michael Garthwaite
+* @date    (last)      19-Jan-2023
 *
 * @author  (original)  Dara Navaei
 * @date    (original)  05-Nov-2019
@@ -171,6 +171,7 @@
 U32 execPostTreatmentMode( void )
 {
     BOOL stop = isStopButtonPressed();
+    HD_POST_TREATMENT_STATE_T priorSubState = currentPostTreatmentState;
 
     switch ( currentPostTreatmentState )
     {
@@ -195,6 +196,11 @@
             break;
     }
 
+    if ( priorSubState != currentPostTreatmentState )
+    {
+        SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_SUB_MODE_CHANGE, priorSubState, currentPostTreatmentState );
+    }
+
     if ( ++postTreatmentPublishTimerCounter >= getU32OverrideValue( &postTreatmentModePublishInterval ) )
     {
         POST_TREATMENT_STATE_DATA_T data;
@@ -510,6 +516,8 @@
  *************************************************************************/
 static void execDrainReservoirs( void )
 {
+    DRAIN_STATE_T priorSubState = currentDrainReservoirState;
+
     switch ( currentDrainReservoirState )
     {
         case DRAIN_DG_DEPRIME_STATE:
@@ -536,6 +544,11 @@
             SET_ALARM_WITH_2_U32_DATA( ALARM_ID_HD_SOFTWARE_FAULT, SW_FAULT_ID_POST_TREATMENT_RESERVOIR_MGMT_INVALID_STATE, currentDrainReservoirState );
             break;
     }
+
+    if ( priorSubState != currentDrainReservoirState )
+    {
+        SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_SUB_STATE_CHANGE, priorSubState, currentDrainReservoirState );
+    }
 }
 
 /*********************************************************************//**