Index: firmware/App/Controllers/DGInterface.c
===================================================================
diff -u -r4cc579577062113856fd266cb65b1ccbe33bb596 -rd0e6b55d2fed933caec5ca8f5b8f19c7f4d7ecea
--- firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 4cc579577062113856fd266cb65b1ccbe33bb596)
+++ firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision d0e6b55d2fed933caec5ca8f5b8f19c7f4d7ecea)
@@ -70,11 +70,10 @@
 static U32 timeStartMS = 0; // TODO is this needed?
 
 // DG sensor data
-static F32 dgDialysateTemp = 0.0;                               ///< Dialysate temperature reported by the DG.
-static F32 dgRedundantDialysateTemp = 0.0;                      ///< Redundant dialysate temperature reported by the DG.
-static F32 dgPrimaryTemp = 0.0;                                 ///< Latest RO water temperature reported by the DG.
-static F32 dgTrimmerTempSet = 0.0;                              ///< Trimmer heater target temperature commanded.
-static F32 dgTrimmerTemp = 0.0;                                 ///< Latest dialysate temperature reported by the DG.
+static F32 dgDialysateTemp;                                     ///< Dialysate temperature reported by the DG.
+static F32 dgRedundantDialysateTemp;                            ///< Redundant dialysate temperature reported by the DG.
+static F32 dgHeatDisinfectTemp;                                 ///< Heat disinfect temperature reported by the DG.
+static F32 dgTrimmerTempSet;                                    ///< Trimmer heater target temperature commanded.
 
 /// Measured weight from load cells.
 static OVERRIDE_F32_T loadCellWeightInGrams[ NUM_OF_LOAD_CELLS ];
@@ -145,6 +144,7 @@
     dgStartCommandSent              = FALSE;
     dgDialysateFlowRateMlMin        = 0.0F;
     dgDialysateFlowDataFreshFlag    = FALSE;
+    dgHeatDisinfectTemp             = 0.0F;
 
     // initialize load cell weights
     for ( i = 0; i < NUM_OF_LOAD_CELLS; i++ )
@@ -464,6 +464,19 @@
 
 /*********************************************************************//**
  * @brief
+ * The getHeatDisinfectTemperatureSensorValue function gets the latest
+ * heat disinfect temperature sensor value.
+ * @details Inputs: dgDialysateTemp
+ * @details Outputs: none
+ * @return the current heat disinfect temperature sensor value
+ *************************************************************************/
+F32 getHeatDisinfectTemperatureSensorValue( void )
+{
+    return dgHeatDisinfectTemp;
+}
+
+/*********************************************************************//**
+ * @brief
  * The getDGDisinfectsStates function returns the DG disinfects readings.
  * @details Inputs: none
  * @details Outputs: none
@@ -534,15 +547,16 @@
  * @details Inputs: none
  * @details Outputs: dgDialysateTemp, dgRedundantDialysateTemp,
  * dgDialysateTemperatureDataFreshFlag
- * @param temp1 dialysate temperature reported by DG
- * @param temp2 redundant dialysate temperature reported by DG
+ * @param tdi dialysate temperature reported by DG
+ * @param tro redundant dialysate temperature reported by DG
+ * @param thd heat disinfect temperature sensor reported by DG
  * @return none
  *************************************************************************/
-void setDialysateTemperatureReadings( F32 temp1, F32 temp2 )
+void setDialysateTemperatureReadings( F32 tdi, F32 tro, F32 thd )
 {
-    dgDialysateTemp = temp1;
-    dgRedundantDialysateTemp = temp2;
-
+    dgDialysateTemp                     = tdi;
+    dgRedundantDialysateTemp            = tro;
+    dgHeatDisinfectTemp                 = thd;
     dgDialysateTemperatureDataFreshFlag = TRUE;
 }
 
Index: firmware/App/Controllers/DGInterface.h
===================================================================
diff -u -rc429cf7f50851acbaca6e800957ef44cc1fa2162 -rd0e6b55d2fed933caec5ca8f5b8f19c7f4d7ecea
--- firmware/App/Controllers/DGInterface.h	(.../DGInterface.h)	(revision c429cf7f50851acbaca6e800957ef44cc1fa2162)
+++ firmware/App/Controllers/DGInterface.h	(.../DGInterface.h)	(revision d0e6b55d2fed933caec5ca8f5b8f19c7f4d7ecea)
@@ -129,12 +129,13 @@
 F32 getReservoirWeightLargeFilter( DG_RESERVOIR_ID_T resID );
 F32 getReservoirBackupWeightLargeFilter( DG_RESERVOIR_ID_T resID );
 F32 getDialysateTemperature( void );
+F32 getHeatDisinfectTemperatureSensorValue( void );
 DG_DISINFECT_UI_STATES_T getDGDisinfectsStates( void );
 DG_MIXING_RATIOS_T getDGMixingRatios( void );
 void getHDVersionDGServiceAndUsageData( DG_SERVICE_AND_USAGE_DATA_T* data );
 
 void setDGOpMode( U32 opMode, U32 subMode );
-void setDialysateTemperatureReadings( F32 temp1, F32 temp2 );
+void setDialysateTemperatureReadings( F32 tdi, F32 tro, F32 thd );
 void setDGReservoirsData( DG_RESERVOIR_ID_T resID, U32 fillVol, U32 drainVol );
 void setDialysateFlowData( F32 flowRate );
 void setNewLoadCellReadings( F32 res1Primary, F32 res1Backup, F32 res2Primary, F32 res2Backup );
Index: firmware/App/Modes/ModeStandby.c
===================================================================
diff -u -r4cc579577062113856fd266cb65b1ccbe33bb596 -rd0e6b55d2fed933caec5ca8f5b8f19c7f4d7ecea
--- firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision 4cc579577062113856fd266cb65b1ccbe33bb596)
+++ firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision d0e6b55d2fed933caec5ca8f5b8f19c7f4d7ecea)
@@ -49,6 +49,7 @@
 #define DISINFECTS_DATA_PUB_INTERVAL          ( 1 * MS_PER_SECOND / TASK_GENERAL_INTERVAL )    ///< Disinfects data publish interval in counts.
 #define DISINFECTS_TIME_INTERVAL_S            ( 2 * SECONDS_IN_A_DAY )                         ///< HD/DG 2-day service interval in seconds.
 #define FLUSH_TIME_INTERVAL_S                 ( 30 * SEC_PER_MIN * MS_PER_SECOND )             ///< Flush time interval in seconds.
+#define MAX_ALLOWED_RO_FILTER_TEMP_FOR_TX_C   44.0F                                            ///< Maximum allowed temperature to start a treatment in C.
 
 // ********** private data **********
 
@@ -310,6 +311,11 @@
         {
             rejReason = REQUEST_REJECT_REASON_DG_DISINFECT_HAS_BEEN_EXPIRED;
         }
+
+        if ( getHeatDisinfectTemperatureSensorValue() > MAX_ALLOWED_RO_FILTER_TEMP_FOR_TX_C )
+        {
+            rejReason = REQUEST_REJECT_REASON_DG_RO_FILTER_TEMPERATURE_OUT_OF_RANGE;
+        }
     }
 
     if ( REQUEST_REJECT_REASON_NONE == rejReason )
Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -r4cc579577062113856fd266cb65b1ccbe33bb596 -rd0e6b55d2fed933caec5ca8f5b8f19c7f4d7ecea
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 4cc579577062113856fd266cb65b1ccbe33bb596)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision d0e6b55d2fed933caec5ca8f5b8f19c7f4d7ecea)
@@ -2355,7 +2355,7 @@
         TEMPERATURE_SENSORS_DATA_T payload;
 
         memcpy( &payload, message->payload, sizeof( TEMPERATURE_SENSORS_DATA_T ) );
-        setDialysateTemperatureReadings( payload.inletDialysate, payload.outletRedundant );
+        setDialysateTemperatureReadings( payload.inletDialysate, payload.outletRedundant, payload.heatDisinfect );
     }
 }