diff --git a/homeassistant/components/august/__init__.py b/homeassistant/components/august/__init__.py
index 38a3ade2d90..3267fbfb0bc 100644
--- a/homeassistant/components/august/__init__.py
+++ b/homeassistant/components/august/__init__.py
@@ -36,11 +36,14 @@ async def async_setup_entry(hass: HomeAssistant, entry: AugustConfigEntry) -> bo
         raise ConfigEntryAuthFailed("Migration to OAuth required")
 
     session = async_create_august_clientsession(hass)
-    implementation = (
-        await config_entry_oauth2_flow.async_get_config_entry_implementation(
-            hass, entry
+    try:
+        implementation = (
+            await config_entry_oauth2_flow.async_get_config_entry_implementation(
+                hass, entry
+            )
         )
-    )
+    except ValueError as err:
+        raise ConfigEntryNotReady("OAuth implementation not available") from err
     oauth_session = config_entry_oauth2_flow.OAuth2Session(hass, entry, implementation)
     august_gateway = AugustGateway(Path(hass.config.config_dir), session, oauth_session)
     try:
diff --git a/tests/components/august/test_init.py b/tests/components/august/test_init.py
index 33517e9e130..ae30c8ad977 100644
--- a/tests/components/august/test_init.py
+++ b/tests/components/august/test_init.py
@@ -1,6 +1,6 @@
 """The tests for the august platform."""
 
-from unittest.mock import Mock
+from unittest.mock import Mock, patch
 
 from aiohttp import ClientResponseError
 import pytest
@@ -33,6 +33,8 @@ from .mocks import (
     _mock_inoperative_august_lock_detail,
     _mock_lock_with_offline_key,
     _mock_operative_august_lock_detail,
+    mock_august_config_entry,
+    mock_client_credentials,
 )
 
 from tests.common import MockConfigEntry
@@ -284,3 +286,18 @@ async def test_oauth_migration_on_legacy_entry(hass: HomeAssistant) -> None:
     assert len(flows) == 1
     assert flows[0]["step_id"] == "pick_implementation"
     assert flows[0]["context"]["source"] == "reauth"
+
+
+async def test_oauth_implementation_not_available(hass: HomeAssistant) -> None:
+    """Test that unavailable OAuth implementation raises ConfigEntryNotReady."""
+    await mock_client_credentials(hass)
+    entry = await mock_august_config_entry(hass)
+
+    with patch(
+        "homeassistant.components.august.config_entry_oauth2_flow.async_get_config_entry_implementation",
+        side_effect=ValueError("Implementation not available"),
+    ):
+        await hass.config_entries.async_setup(entry.entry_id)
+        await hass.async_block_till_done()
+
+    assert entry.state is ConfigEntryState.SETUP_RETRY