diff --git a/homeassistant/components/teslemetry/sensor.py b/homeassistant/components/teslemetry/sensor.py
index 56c8830d736..f1859ad39de 100644
--- a/homeassistant/components/teslemetry/sensor.py
+++ b/homeassistant/components/teslemetry/sensor.py
@@ -68,7 +68,7 @@ class TeslemetryVehicleSensorEntityDescription(SensorEntityDescription):
 
     polling: bool = False
     polling_value_fn: Callable[[StateType], StateType] = lambda x: x
-    polling_available_fn: Callable[[StateType], bool] = lambda x: x is not None
+    nullable: bool = False
     streaming_key: Signal | None = None
     streaming_value_fn: Callable[[str | int | float], StateType] = lambda x: x
     streaming_firmware: str = "2024.26"
@@ -210,7 +210,7 @@ VEHICLE_DESCRIPTIONS: tuple[TeslemetryVehicleSensorEntityDescription, ...] = (
     TeslemetryVehicleSensorEntityDescription(
         key="drive_state_shift_state",
         polling=True,
-        polling_available_fn=lambda x: True,
+        nullable=True,
         polling_value_fn=lambda x: SHIFT_STATES.get(str(x), "p"),
         streaming_key=Signal.GEAR,
         streaming_value_fn=lambda x: str(ShiftState.get(x, "P")).lower(),
@@ -622,10 +622,10 @@ class TeslemetryStreamSensorEntity(TeslemetryVehicleStreamEntity, RestoreSensor)
 
     def _async_value_from_stream(self, value) -> None:
         """Update the value of the entity."""
-        if value is None:
-            self._attr_native_value = None
-        else:
+        if self.entity_description.nullable or value is not None:
             self._attr_native_value = self.entity_description.streaming_value_fn(value)
+        else:
+            self._attr_native_value = None
 
 
 class TeslemetryVehicleSensorEntity(TeslemetryVehicleEntity, SensorEntity):
@@ -644,7 +644,7 @@ class TeslemetryVehicleSensorEntity(TeslemetryVehicleEntity, SensorEntity):
 
     def _async_update_attrs(self) -> None:
         """Update the attributes of the sensor."""
-        if self.entity_description.polling_available_fn(self._value):
+        if self.entity_description.nullable or self._value is not None:
             self._attr_available = True
             self._attr_native_value = self.entity_description.polling_value_fn(
                 self._value
diff --git a/homeassistant/components/tessie/sensor.py b/homeassistant/components/tessie/sensor.py
index 1c26ad633f3..e5b476057fa 100644
--- a/homeassistant/components/tessie/sensor.py
+++ b/homeassistant/components/tessie/sensor.py
@@ -148,7 +148,7 @@ DESCRIPTIONS: tuple[TessieSensorEntityDescription, ...] = (
         key="drive_state_shift_state",
         options=["p", "d", "r", "n"],
         device_class=SensorDeviceClass.ENUM,
-        value_fn=lambda x: x.lower() if isinstance(x, str) else x,
+        value_fn=lambda x: x.lower() if isinstance(x, str) else "p",
     ),
     TessieSensorEntityDescription(
         key="vehicle_state_odometer",
diff --git a/tests/components/tessie/snapshots/test_sensor.ambr b/tests/components/tessie/snapshots/test_sensor.ambr
index 5465f89d808..b40cf204bca 100644
--- a/tests/components/tessie/snapshots/test_sensor.ambr
+++ b/tests/components/tessie/snapshots/test_sensor.ambr
@@ -1614,7 +1614,7 @@
     'last_changed': <ANY>,
     'last_reported': <ANY>,
     'last_updated': <ANY>,
-    'state': 'unknown',
+    'state': 'p',
   })
 # ---
 # name: test_sensors[sensor.test_speed-entry]