diff --git a/homeassistant/components/opentherm_gw/config_flow.py b/homeassistant/components/opentherm_gw/config_flow.py
index 4afc508b8ee..60d367db5a1 100644
--- a/homeassistant/components/opentherm_gw/config_flow.py
+++ b/homeassistant/components/opentherm_gw/config_flow.py
@@ -58,10 +58,8 @@ class OpenThermGwConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
 
             try:
                 res = await asyncio.wait_for(test_connection(), timeout=10)
-            except asyncio.TimeoutError:
-                return self._show_form({"base": "timeout"})
-            except SerialException:
-                return self._show_form({"base": "serial_error"})
+            except (asyncio.TimeoutError, SerialException):
+                return self._show_form({"base": "cannot_connect"})
 
             if res:
                 return self._create_entry(gw_id, name, device)
diff --git a/homeassistant/components/opentherm_gw/strings.json b/homeassistant/components/opentherm_gw/strings.json
index 332b97eb5ee..306529e7be1 100644
--- a/homeassistant/components/opentherm_gw/strings.json
+++ b/homeassistant/components/opentherm_gw/strings.json
@@ -11,10 +11,9 @@
       }
     },
     "error": {
-      "already_configured": "Gateway already configured",
+      "already_configured": "[%key:common::config_flow::abort::already_configured_device%]",
       "id_exists": "Gateway id already exists",
-      "serial_error": "Error connecting to device",
-      "timeout": "Connection attempt timed out"
+      "cannot_connect": "[%key:common::config_flow::error::cannot_connect%]"
     }
   },
   "options": {
diff --git a/tests/components/opentherm_gw/test_config_flow.py b/tests/components/opentherm_gw/test_config_flow.py
index d2d31d97628..2f4c171cf36 100644
--- a/tests/components/opentherm_gw/test_config_flow.py
+++ b/tests/components/opentherm_gw/test_config_flow.py
@@ -148,7 +148,7 @@ async def test_form_connection_timeout(hass):
         )
 
     assert result2["type"] == "form"
-    assert result2["errors"] == {"base": "timeout"}
+    assert result2["errors"] == {"base": "cannot_connect"}
     assert len(mock_connect.mock_calls) == 1
 
 
@@ -164,7 +164,7 @@ async def test_form_connection_error(hass):
         )
 
     assert result2["type"] == "form"
-    assert result2["errors"] == {"base": "serial_error"}
+    assert result2["errors"] == {"base": "cannot_connect"}
     assert len(mock_connect.mock_calls) == 1