diff --git a/libs/color-sensor/color.ts b/libs/color-sensor/color.ts
index 9b88e32d..c1c624c1 100644
--- a/libs/color-sensor/color.ts
+++ b/libs/color-sensor/color.ts
@@ -94,6 +94,7 @@ namespace sensors {
         }
 
         _update(prev: number, curr: number) {
+            if (curr == null) return;
             if (this.mode == ColorSensorMode.Color)
                 control.raiseEvent(this._id, this._colorEventValue(curr));
             else
diff --git a/sim/state/sensor.ts b/sim/state/sensor.ts
index ccef210b..7c37ffdd 100644
--- a/sim/state/sensor.ts
+++ b/sim/state/sensor.ts
@@ -5,6 +5,7 @@ namespace pxsim {
 
         protected mode: number;
         protected valueChanged: boolean;
+        protected modeChanged: boolean;
 
         constructor(port: number) {
             super(port);
@@ -24,6 +25,8 @@ namespace pxsim {
 
         setMode(mode: number) {
             this.mode = mode;
+            this.changed = true;
+            this.modeChanged = true;
         }
 
         getMode() {
@@ -44,6 +47,12 @@ namespace pxsim {
             return res;
         }
 
+        modeChange() {
+            const res = this.modeChanged;
+            this.modeChanged = false;
+            return res;
+        }
+
         setChangedState() {
             this.changed = true;
             this.valueChanged = false;
diff --git a/sim/visuals/board.ts b/sim/visuals/board.ts
index 35b426c0..1a8eafb7 100644
--- a/sim/visuals/board.ts
+++ b/sim/visuals/board.ts
@@ -183,8 +183,8 @@ namespace pxsim.visuals {
             this.layoutView.updateTheme(theme);
         }
 
-        private getControlForNode(id: NodeType, port: number) {
-            if (this.cachedControlNodes[id] && this.cachedControlNodes[id][port]) {
+        private getControlForNode(id: NodeType, port: number, useCache = true) {
+            if (useCache && this.cachedControlNodes[id] && this.cachedControlNodes[id][port]) {
                 return this.cachedControlNodes[id][port];
             }
 
@@ -406,7 +406,7 @@ namespace pxsim.visuals {
                 if (view) {
                     const isSelected = EV3View.isPreviousInputSelected(index, node.id) || view.getSelected();
                     if (isSelected && !view.getSelected()) view.setSelected(true);
-                    const control = isSelected ? this.getControlForNode(node.id, index) : undefined;
+                    const control = isSelected ? this.getControlForNode(node.id, index, !node.modeChange()) : undefined;
                     const closeIcon = control ? this.getCloseIconView() : undefined;
                     this.layoutView.setInput(index, view, control, closeIcon);
                     view.updateState();