diff --git a/homeassistant/components/emoncms/sensor.py b/homeassistant/components/emoncms/sensor.py
index c981fa0cf6c..cf21cb75847 100644
--- a/homeassistant/components/emoncms/sensor.py
+++ b/homeassistant/components/emoncms/sensor.py
@@ -169,7 +169,6 @@ class EmonCmsSensor(SensorEntity):
         self._value_template = value_template
         self._attr_native_unit_of_measurement = unit_of_measurement
         self._sensorid = sensorid
-        self._elem = elem
 
         if unit_of_measurement in ("kWh", "Wh"):
             self._attr_device_class = SensorDeviceClass.ENERGY
@@ -195,7 +194,24 @@ class EmonCmsSensor(SensorEntity):
         elif unit_of_measurement == "hPa":
             self._attr_device_class = SensorDeviceClass.PRESSURE
             self._attr_state_class = SensorStateClass.MEASUREMENT
+        self._update_attributes(elem)
 
+    def _update_attributes(self, elem: dict[str, Any]) -> None:
+        """Update entity attributes."""
+        self._attr_extra_state_attributes = {
+            ATTR_FEEDID: elem["id"],
+            ATTR_TAG: elem["tag"],
+            ATTR_FEEDNAME: elem["name"],
+        }
+        if elem["value"] is not None:
+            self._attr_extra_state_attributes[ATTR_SIZE] = elem["size"]
+            self._attr_extra_state_attributes[ATTR_USERID] = elem["userid"]
+            self._attr_extra_state_attributes[ATTR_LASTUPDATETIME] = elem["time"]
+            self._attr_extra_state_attributes[ATTR_LASTUPDATETIMESTR] = (
+                template.timestamp_local(float(elem["time"]))
+            )
+
+        self._attr_native_value = None
         if self._value_template is not None:
             self._attr_native_value = (
                 self._value_template.render_with_possible_json_value(
@@ -204,21 +220,6 @@ class EmonCmsSensor(SensorEntity):
             )
         elif elem["value"] is not None:
             self._attr_native_value = round(float(elem["value"]), DECIMALS)
-        else:
-            self._attr_native_value = None
-
-    @property
-    def extra_state_attributes(self) -> dict[str, Any]:
-        """Return the sensor extra attributes."""
-        return {
-            ATTR_FEEDID: self._elem["id"],
-            ATTR_TAG: self._elem["tag"],
-            ATTR_FEEDNAME: self._elem["name"],
-            ATTR_SIZE: self._elem["size"],
-            ATTR_USERID: self._elem["userid"],
-            ATTR_LASTUPDATETIME: self._elem["time"],
-            ATTR_LASTUPDATETIMESTR: template.timestamp_local(float(self._elem["time"])),
-        }
 
     def update(self) -> None:
         """Get the latest data and updates the state."""
@@ -246,18 +247,7 @@ class EmonCmsSensor(SensorEntity):
         if elem is None:
             return
 
-        self._elem = elem
-
-        if self._value_template is not None:
-            self._attr_native_value = (
-                self._value_template.render_with_possible_json_value(
-                    elem["value"], STATE_UNKNOWN
-                )
-            )
-        elif elem["value"] is not None:
-            self._attr_native_value = round(float(elem["value"]), DECIMALS)
-        else:
-            self._attr_native_value = None
+        self._update_attributes(elem)
 
 
 class EmonCmsData: