diff --git a/ev3sim/attach_bot.py b/ev3sim/attach_bot.py
index 47c17ed7..52791fda 100644
--- a/ev3sim/attach_bot.py
+++ b/ev3sim/attach_bot.py
@@ -73,6 +73,10 @@ def handle_recv(msg_type, msg):
                     tick = msg["tick"]
                     tick_rate = msg["tick_rate"]
                     current_data = msg["data"]
+                    if isinstance(current_data, str):
+                        # Not pretty but it works.
+                        e = Exception(current_data)
+                        raise e
                     for ev in msg["events"]:
                         cur_events.put(ev)
                     return msg_type, msg
@@ -298,6 +302,8 @@ def seek(self, i):
 
                 def write(self, value):
                     send_q.put((DEVICE_WRITE, (f"{self.k2} {self.k3} {self.k4}", value.decode())))
+                    while self.k4 == "mode" and current_data[self.k2][self.k3][self.k4] != value.decode():
+                        wait_for_tick()
 
                 def flush(self):
                     pass
diff --git a/ev3sim/devices/colour/base.py b/ev3sim/devices/colour/base.py
index 0d2e72c4..d03277ea 100644
--- a/ev3sim/devices/colour/base.py
+++ b/ev3sim/devices/colour/base.py
@@ -5,6 +5,8 @@
 class ColourSensorMixin:
 
     RGB_RAW = "RGB-RAW"
+    COL_REFLECT = "COL-REFLECT"
+    COL_COLOR = "COL-COLOR"
 
     device_type = "lego-sensor"
     mode = RGB_RAW
@@ -44,6 +46,10 @@ def toObject(self):
         }
         if self.mode == self.RGB_RAW:
             data["value0"], data["value1"], data["value2"] = res
+        elif self.mode == self.COL_REFLECT:
+            data["value0"] = self.reflected_light_intensity()
+        elif self.mode == self.COL_COLOR:
+            data["value0"] = self.predict_color()
         else:
             raise ValueError(f"Unhandled mode {self.mode}")
         return data
diff --git a/ev3sim/devices/colour/ev3.py b/ev3sim/devices/colour/ev3.py
index 84f1e48d..f2da3633 100644
--- a/ev3sim/devices/colour/ev3.py
+++ b/ev3sim/devices/colour/ev3.py
@@ -31,6 +31,18 @@ class ColorSensor(ColourSensorMixin, Device):
     MIN_RGB_BIAS = 230
     STARTING_CALIBRATION = 300
 
+    PREDICTION_VECTORS = [
+        (0, 0, 0),
+        (0, 0, 255),
+        (85, 166, 48),
+        (255, 255, 0),
+        (255, 0, 0),
+        (255, 255, 255),
+        (165, 42, 42),
+    ]
+    PREDICTION_INCREASE_REQUIREMENT = 60
+    PREDICTION_LARGEST_DIFFERENCE = 110
+
     def generateBias(self):
         self.saved_raw = (0, 0, 0)
         if ScriptLoader.RANDOMISE_SENSORS:
@@ -102,8 +114,19 @@ def rgb(self):
         ]
 
     def reflected_light_intensity(self):
-        """Not implemented"""
-        raise NotImplementedError("`reflected_light_intensity` is currently not implemented.")
+        r, g, b = self.rgb()
+        return int((r / 255 + g / 255 + b / 255) * 100 / 3)
+
+    def predict_color(self):
+        r, g, b = self.rgb()
+        colors = sorted(
+            [(abs(r - c[0]) + abs(g - c[1]) + abs(b - c[2]), i) for i, c in enumerate(self.PREDICTION_VECTORS)]
+        )
+        if colors[0][0] > self.PREDICTION_LARGEST_DIFFERENCE:
+            return 0
+        if colors[1][0] - colors[0][0] < self.PREDICTION_INCREASE_REQUIREMENT:
+            return 0
+        return colors[0][1] + 1
 
     def reset(self):
         self.mode = self.RGB_RAW
diff --git a/ev3sim/robot.py b/ev3sim/robot.py
index 6b2e6d6b..a7d6cb77 100644
--- a/ev3sim/robot.py
+++ b/ev3sim/robot.py
@@ -123,7 +123,11 @@ def collectDeviceData(self):
         for port, device in self.devices.items():
             if device.device_type not in res:
                 res[device.device_type] = {}
-            res[device.device_type][device._getObjName(port)] = device.toObject()
+            try:
+                res[device.device_type][device._getObjName(port)] = device.toObject()
+            except Exception as e:
+                # Something has failed, so let the attached script know.
+                return str(e)
         return res
 
     def resetBot(self):