Index: firmware/App/Controllers/PresOccl.c
===================================================================
diff -u -r37a9fd8f15e413db5337371a7d1a1cb65567af7c -r6eef422e39bed332f9958b165f8e64a23185a170
--- firmware/App/Controllers/PresOccl.c	(.../PresOccl.c)	(revision 37a9fd8f15e413db5337371a7d1a1cb65567af7c)
+++ firmware/App/Controllers/PresOccl.c	(.../PresOccl.c)	(revision 6eef422e39bed332f9958b165f8e64a23185a170)
@@ -669,7 +669,7 @@
 static void checkOcclusions( void )
 {
     U32 bpOccl = getMeasuredBloodPumpOcclusion();
-    BOOL outOfRange = ( bpOccl < MIN_OCCLUSION_COUNTS || bpOccl > MAX_OCCLUSION_COUNTS ? TRUE : FALSE );
+    BOOL outOfRange = ( bpOccl < MIN_OCCLUSION_COUNTS || bpOccl > MAX_OCCLUSION_COUNTS ? TRUE : FALSE );
 
     if ( getSoftwareConfigStatus( SW_CONFIG_DISABLE_PRESSURE_CHECKS ) != SW_CONFIG_ENABLE_VALUE )
     {
@@ -679,14 +679,38 @@
             SET_ALARM_WITH_1_U32_DATA( ALARM_ID_HD_BP_OCCLUSION_OUT_OF_RANGE, bpOccl );
         }
 
-        // Check for occlusion
-        if ( bpOccl > ( OCCLUSION_THRESHOLD_OFFSET + bloodPumpOcclusionAfterCartridgeInstall ) )
+        // Check for occlusion in PreTreatment modes when the cartridge is installed
+        // and setOcclusionInstallLevel has been called.
+        if( MODE_PRET == getCurrentOperationMode() )
         {
-            signalBloodPumpHardStop();  // Stop pump immediately
-            SET_ALARM_WITH_1_U32_DATA( ALARM_ID_OCCLUSION_BLOOD_PUMP, bpOccl )
+            if( getPreTreatmentSubState() > HD_PRE_TREATMENT_CART_INSTALL_STATE && getDrySelfTestsState() > DRY_SELF_TESTS_START_STATE )
+            {
+                // Check for occlusion
+                if ( bpOccl > ( OCCLUSION_THRESHOLD_OFFSET + bloodPumpOcclusionAfterCartridgeInstall ) )
+                {
+                    signalBloodPumpHardStop();  // Stop pump immediately
+                    SET_ALARM_WITH_1_U32_DATA( ALARM_ID_OCCLUSION_BLOOD_PUMP, bpOccl )
+                }
+            }
         }
-        else if ( bpOccl <= ( OCCLUSION_CLEAR_THRESHOLD_OFFSET + bloodPumpOcclusionAfterCartridgeInstall ) )
+
+        // Check for occlusion in PreTreatment modes where pumps are moving
+        else if( MODE_TREA == getCurrentOperationMode() )
         {
+            if( TREATMENT_STOP_STATE != getTreatmentState())
+            {
+                // Check for occlusion
+                if ( bpOccl > ( OCCLUSION_THRESHOLD_OFFSET + bloodPumpOcclusionAfterCartridgeInstall ) )
+                {
+                    signalBloodPumpHardStop();  // Stop pump immediately
+                    SET_ALARM_WITH_1_U32_DATA( ALARM_ID_OCCLUSION_BLOOD_PUMP, bpOccl )
+                }
+            }
+        }
+
+        // Clear alarm regardless of op mode once conditions are met.
+        if ( bpOccl <= ( OCCLUSION_CLEAR_THRESHOLD_OFFSET + bloodPumpOcclusionAfterCartridgeInstall ) )
+        {
             clearAlarmCondition( ALARM_ID_OCCLUSION_BLOOD_PUMP );
         }
     }