diff --git a/homeassistant/components/ondilo_ico/sensor.py b/homeassistant/components/ondilo_ico/sensor.py
index ddc4a94853f..da5ccae11a5 100644
--- a/homeassistant/components/ondilo_ico/sensor.py
+++ b/homeassistant/components/ondilo_ico/sensor.py
@@ -12,6 +12,7 @@ from homeassistant.config_entries import ConfigEntry
 from homeassistant.const import (
     CONCENTRATION_PARTS_PER_MILLION,
     PERCENTAGE,
+    EntityCategory,
     UnitOfElectricPotential,
     UnitOfTemperature,
 )
@@ -56,12 +57,14 @@ SENSOR_TYPES: tuple[SensorEntityDescription, ...] = (
         key="battery",
         native_unit_of_measurement=PERCENTAGE,
         device_class=SensorDeviceClass.BATTERY,
+        entity_category=EntityCategory.DIAGNOSTIC,
         state_class=SensorStateClass.MEASUREMENT,
     ),
     SensorEntityDescription(
         key="rssi",
         translation_key="rssi",
         native_unit_of_measurement=PERCENTAGE,
+        entity_category=EntityCategory.DIAGNOSTIC,
         state_class=SensorStateClass.MEASUREMENT,
     ),
     SensorEntityDescription(
diff --git a/tests/components/ondilo_ico/snapshots/test_sensor.ambr b/tests/components/ondilo_ico/snapshots/test_sensor.ambr
index 84a2d3da4cb..7df2bfc22ce 100644
--- a/tests/components/ondilo_ico/snapshots/test_sensor.ambr
+++ b/tests/components/ondilo_ico/snapshots/test_sensor.ambr
@@ -13,7 +13,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.pool_1_battery',
     'has_entity_name': True,
     'hidden_by': None,
@@ -167,7 +167,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.pool_1_rssi',
     'has_entity_name': True,
     'hidden_by': None,
@@ -372,7 +372,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.pool_2_battery',
     'has_entity_name': True,
     'hidden_by': None,
@@ -526,7 +526,7 @@
     'device_id': <ANY>,
     'disabled_by': None,
     'domain': 'sensor',
-    'entity_category': None,
+    'entity_category': <EntityCategory.DIAGNOSTIC: 'diagnostic'>,
     'entity_id': 'sensor.pool_2_rssi',
     'has_entity_name': True,
     'hidden_by': None,