Index: firmware/App/Modes/ModeStandby.c
===================================================================
diff -u -r9f01014483a2ec46a19bdb7ce7ab97b007f83cbd -rdaf4763d6f40baf4cbc2f9d88aba7d9faf588ad6
--- firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision 9f01014483a2ec46a19bdb7ce7ab97b007f83cbd)
+++ firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision daf4763d6f40baf4cbc2f9d88aba7d9faf588ad6)
@@ -558,16 +558,16 @@
 BOOL startDGChemicalDisinfectFlush( void )
 {
     BOOL status = FALSE;
+    DG_CMD_RESPONSE_T cmdResponse;
 
+    cmdResponse.commandID  = DG_CMD_START_CHEM_DISINFECT_FLUSH;
+    cmdResponse.rejected   = FALSE;
+    cmdResponse.rejectCode = DG_CMD_REQUEST_REJECT_REASON_NONE;
+
     // If DG is in standby mode and the standby mode is in Idle, request chemical disinfect flush
     // Chemical disinfect flush cannot be run in solo mode because the user has to confirm that the acid is inserted or removed
     if ( ( DG_MODE_STAN == getCurrentOperationMode() ) && ( DG_STANDBY_MODE_STATE_IDLE == standbyState ) )
     {
-        DG_CMD_RESPONSE_T cmdResponse;
-
-        cmdResponse.commandID  = DG_CMD_START_CHEM_DISINFECT_FLUSH;
-        cmdResponse.rejected   = FALSE;
-        cmdResponse.rejectCode = DG_CMD_REQUEST_REJECT_REASON_NONE;
         OPN_CLS_STATE_T concCap = getSwitchStatus( CONCENTRATE_CAP );
         OPN_CLS_STATE_T diaCap  = getSwitchStatus( DIALYSATE_CAP );
 
@@ -591,10 +591,15 @@
             pendingStartDGChemicalDisinfectFlushRequest = TRUE;
             status                                      = TRUE;
         }
-
-        sendCommandResponseMsg( &cmdResponse );
     }
+    else
+    {
+        cmdResponse.rejected   = TRUE;
+        cmdResponse.rejectCode = REQUEST_REJECT_REASON_DG_NOT_IN_STANDBY_IDLE_STATE;
+    }
 
+    sendCommandResponseMsg( &cmdResponse );
+
     return status;
 }