diff --git a/README.md b/README.md
index cf89540..19b43a7 100644
--- a/README.md
+++ b/README.md
@@ -282,6 +282,9 @@ https://www.gnu.org/licenses/gpl-3.0.html
 - Keep looking to see if there is a time sync mechanism
 - Use the config ver and status ver check in simulator to make sure partial block updates are acceptable
 
+## Done/Fixed in 1.0.10
+ - Handle TempNotValid error
+
 ## Done/Fixed in 1.0.9
  - Fixed broken EcoMode switch that 1.0.8 introduced
  - Added pump and blower sensors to show P<n> & BL device states because buttons now
diff --git a/src/geckolib/_version.py b/src/geckolib/_version.py
index e85f274..07007d1 100644
--- a/src/geckolib/_version.py
+++ b/src/geckolib/_version.py
@@ -1,3 +1,3 @@
 """Single module version."""
 
-VERSION = "1.0.9"
+VERSION = "1.0.10"
diff --git a/src/geckolib/automation/heater.py b/src/geckolib/automation/heater.py
index e7af005..25e4f96 100644
--- a/src/geckolib/automation/heater.py
+++ b/src/geckolib/automation/heater.py
@@ -2,8 +2,9 @@
 
 from __future__ import annotations
 
+import logging
 from abc import abstractmethod
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 
 from geckolib.automation.power import GeckoPower
 from geckolib.const import GeckoConstants
@@ -13,6 +14,8 @@
 if TYPE_CHECKING:
     from geckolib.automation.async_facade import GeckoAsyncFacade
 
+_LOGGER = logging.getLogger(__name__)
+
 
 class GeckoWaterHeaterAbstract(GeckoPower):
     """Abstract base for water heaters."""
@@ -71,6 +74,7 @@ def __init__(self, facade: GeckoAsyncFacade) -> None:
         self._cooling_action_sensor = None
         self._min_temp_sensor = None
         self._max_temp_sensor = None
+        self._temp_not_valid_sensor = None
 
         # Attempt to locate the various items needed from the spa accessors
         self._temperature_unit_accessor = self._spa.accessors[
@@ -126,6 +130,12 @@ def __init__(self, facade: GeckoAsyncFacade) -> None:
                 self._spa.accessors[GeckoConstants.KEY_MAX_SETPOINT_G],
                 self._temperature_unit_accessor,
             )
+        if GeckoConstants.KEY_TEMP_NOT_VALID in self._spa.accessors:
+            self._temp_not_valid_sensor = GeckoSensor(
+                self.facade,
+                "Temp Not Valid",
+                self._spa.accessors[GeckoConstants.KEY_TEMP_NOT_VALID],
+            )
 
         # Setup change observers
         for sensor in [
@@ -137,10 +147,13 @@ def __init__(self, facade: GeckoAsyncFacade) -> None:
             self._cooling_action_sensor,
             self._min_temp_sensor,
             self._max_temp_sensor,
+            self._temp_not_valid_sensor,
         ]:
             if sensor is not None:
                 sensor.watch(self._on_change)
 
+        self._on_change(None, None, None)
+
     @property
     def target_temperature_sensor(self) -> GeckoSensor:
         """Get the target temperature sensor object."""
@@ -262,6 +275,13 @@ def __str__(self) -> str:
             )
         return f"{self.name}: Not present"
 
+    def _on_change(
+        self, sender: Any = None, old_value: Any = None, new_value: Any = None
+    ) -> None:
+        if self._temp_not_valid_sensor is not None:
+            self.set_availability(is_available=not self._temp_not_valid_sensor.state)
+        return super()._on_change(sender, old_value, new_value)
+
     @property
     def monitor(self) -> str:
         """Get monitor string."""
diff --git a/src/geckolib/automation/sensors.py b/src/geckolib/automation/sensors.py
index 6e96293..6128dac 100644
--- a/src/geckolib/automation/sensors.py
+++ b/src/geckolib/automation/sensors.py
@@ -157,3 +157,5 @@ def update_state(
             _LOGGER.debug("Error sensor state is %s", self.state)
         else:
             self._state = "None"
+
+        self._on_change(None, None, None)
diff --git a/src/geckolib/const.py b/src/geckolib/const.py
index 24dcf6a..e042be4 100644
--- a/src/geckolib/const.py
+++ b/src/geckolib/const.py
@@ -48,6 +48,7 @@ class GeckoConstants:
     KEY_DISPLAYED_TEMP_G = "DisplayedTempG"
     KEY_HEATING = "Heating"
     KEY_COOLINGDOWN = "CoolingDown"
+    KEY_TEMP_NOT_VALID = "TempNotValid"
     KEY_PUMP_1 = "P1"
     KEY_PUMP_2 = "P2"
     KEY_PUMP_3 = "P3"