diff --git a/src/widgets/atcoreinstancewidget.cpp b/src/widgets/atcoreinstancewidget.cpp
--- a/src/widgets/atcoreinstancewidget.cpp
+++ b/src/widgets/atcoreinstancewidget.cpp
@@ -232,6 +232,7 @@
             m_printWidget->updateFanCount(2);
         }
     } else {
+        m_bedExtWidget->resetTargetTemperatures();
         m_core.closeConnection();
         emit(connectionChanged(i18n("Connect a Printer")));
     }
diff --git a/src/widgets/bedextruderwidget.h b/src/widgets/bedextruderwidget.h
--- a/src/widgets/bedextruderwidget.h
+++ b/src/widgets/bedextruderwidget.h
@@ -40,6 +40,7 @@
     void updateBedTargetTemp(const float temp);
     void updateExtTargetTemp(const float temp);
     void setBedThermoHidden(bool hidden);
+    void resetTargetTemperatures();
 
 private:
     int m_extruderCount = 0;
diff --git a/src/widgets/bedextruderwidget.cpp b/src/widgets/bedextruderwidget.cpp
--- a/src/widgets/bedextruderwidget.cpp
+++ b/src/widgets/bedextruderwidget.cpp
@@ -128,3 +128,9 @@
 {
     m_bedThermo->setHidden(hidden);
 }
+
+void BedExtruderWidget::resetTargetTemperatures()
+{
+    m_bedThermo->setTargetTemperature(0);
+    m_extruderThermo->setTargetTemperature(0);
+}