diff --git a/custom_components/zaptec/zaptec/api.py b/custom_components/zaptec/zaptec/api.py
index b906c87a..ef61d6a2 100644
--- a/custom_components/zaptec/zaptec/api.py
+++ b/custom_components/zaptec/zaptec/api.py
@@ -32,6 +32,7 @@
     API_TIMEOUT,
     API_URL,
     CHARGER_EXCLUDES,
+    CLEARABLE_OBSERVATIONS,
     DEFAULT_MAX_CURRENT,
     MAX_DEBUG_TEXT_LEN_ON_500,
     MISSING,
@@ -209,6 +210,8 @@ def state_to_attrs(
                 _LOGGER.debug("Excluding key %s entry: %s", skey, item)
                 continue
             value = item.get("Value", item.get("ValueAsString", MISSING))
+            if value is MISSING and str(skey) in CLEARABLE_OBSERVATIONS:
+                value = ""
             if value is not MISSING:
                 kv = keydict.get(skey, f"{key} {skey}")
                 if kv in out:
diff --git a/custom_components/zaptec/zaptec/const.py b/custom_components/zaptec/zaptec/const.py
index 10e9f589..0152334f 100644
--- a/custom_components/zaptec/zaptec/const.py
+++ b/custom_components/zaptec/zaptec/const.py
@@ -69,6 +69,14 @@ class Missing:
 TRUTHY = ["true", "1", "on", "yes", 1, True]
 FALSY = ["false", "0", "off", "no", 0, False]
 
+CLEARABLE_OBSERVATIONS = {
+    "721",  # SessionIdentifier
+    "722",  # ChargerCurrentUserUuid
+}
+"""Observations that Zaptec clears by sending them without any value, rather
+than with an empty one. Without mapping them to an empty value, the previous
+session's value would persist indefinitely."""
+
 # Charger state attributes that should be excluded from being set as class
 # attributes. Use strings.
 CHARGER_EXCLUDES = {
diff --git a/tests/zaptec/test_api.py b/tests/zaptec/test_api.py
index df1c55ac..6213035f 100644
--- a/tests/zaptec/test_api.py
+++ b/tests/zaptec/test_api.py
@@ -381,6 +381,19 @@ def test_state_to_attrs_skips_missing_key_and_missing_value() -> None:
     assert out == {}
 
 
+def test_state_to_attrs_clears_session_observation_without_value() -> None:
+    """A session observation sent without a value clears the attribute.
+
+    Zaptec signals "no session" by sending SessionIdentifier (721) and
+    ChargerCurrentUserUuid (722) with no ValueAsString at all, rather than
+    with an empty value.
+    """
+    data = [{"StateId": 721}, {"StateId": 722}]
+    keydict = {721: "SessionIdentifier", 722: "ChargerCurrentUserUuid"}
+    out = ZaptecBase.state_to_attrs(data, "StateId", keydict)
+    assert out == {"SessionIdentifier": "", "ChargerCurrentUserUuid": ""}
+
+
 def test_state_to_attrs_excludes() -> None:
     """Excluded ids are dropped."""
     data = [
@@ -857,6 +870,30 @@ async def test_poll_state_happy_path(monkeypatch: pytest.MonkeyPatch) -> None:
     charger.set_attributes.assert_called_once()
 
 
+@pytest.mark.asyncio
+async def test_poll_state_clears_session_attribute_when_value_is_gone(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """A session that ends clears the attribute instead of leaving it stale."""
+    monkeypatch.setattr(ZCONST, "observations", {722: "ChargerCurrentUserUuid"}, raising=False)
+    monkeypatch.setattr("custom_components.zaptec.zaptec.api.validate", Mock())
+    charger, _ = _charger_with_session(
+        [
+            FakeResponse(
+                HTTPStatus.OK,
+                json_data=[{"StateId": 722, "ValueAsString": "nfc-abc123"}],
+            ),
+            FakeResponse(HTTPStatus.OK, json_data=[{"StateId": 722}]),
+        ]
+    )
+
+    await charger.poll_state()
+    assert charger.get("charger_current_user_uuid") == "nfc-abc123"
+
+    await charger.poll_state()
+    assert charger.get("charger_current_user_uuid") == ""
+
+
 @pytest.mark.asyncio
 async def test_poll_state_forbidden_is_ignored() -> None:
     """A 403 on the state endpoint is swallowed (no attribute update)."""