diff --git a/ingestor/engines/active_read.py b/ingestor/engines/active_read.py
index 6aedf7e..cb2cacd 100644
--- a/ingestor/engines/active_read.py
+++ b/ingestor/engines/active_read.py
@@ -89,7 +89,7 @@ class ActiveReadEngine(SientiaMonitoring):
 
     @staticmethod
     def _extract(dv):
-        status_name = dv.StatusCode_.name if dv.StatusCode_ is not None else None
+        status_name = dv.StatusCode.name if dv.StatusCode is not None else None
         return dv.Value.Value, status_name, dv.SourceTimestamp, dv.ServerTimestamp
 
     @staticmethod
diff --git a/ingestor/engines/write.py b/ingestor/engines/write.py
index 3b297d6..675cb74 100644
--- a/ingestor/engines/write.py
+++ b/ingestor/engines/write.py
@@ -7,7 +7,6 @@ to the server, a rate-limit floor between writes, and OPC error typing.
 
 import asyncio
 from dataclasses import dataclass
-from datetime import datetime
 
 from asyncua import ua
 from asyncua.ua.uaerrors import UaStatusCodeError
@@ -146,12 +145,12 @@ class WriteEngine(SientiaMonitoring):
         variant = ua.Variant(typed_value, self._variant_type(cmd['data_type']))
         write_quality = cmd.get('write_quality', self.write_quality)
         write_timestamp = cmd.get('write_timestamp', self.write_timestamp)
-        # NOTE: DataValue.StatusCode_ default_factory populates a Good status
-        # even when omitted, so "off" must pass StatusCode_=None explicitly
+        # NOTE: DataValue.StatusCode default_factory populates a Good status
+        # even when omitted, so "off" must pass StatusCode=None explicitly
         # or the flag silently no-ops.
-        status_code = ua.StatusCode(ua.StatusCodes.Good) if write_quality else None
-        source_ts = datetime.fromisoformat(cmd['timestamp']) if write_timestamp else None
-        return ua.DataValue(variant, StatusCode_=status_code, SourceTimestamp=source_ts)
+        status_code = ua.StatusCode(ua.UInt32(ua.StatusCodes.Good)) if write_quality else None
+        source_ts = ua.DateTime.fromisoformat(cmd['timestamp']) if write_timestamp else None
+        return ua.DataValue(variant, StatusCode=status_code, SourceTimestamp=source_ts)
 
     def _is_session_bad(self, exc: Exception) -> bool:
         return isinstance(exc, UaStatusCodeError) and type(exc).__name__ in _SESSION_BAD_NAMES
diff --git a/tests/unit/engines/test_active_read.py b/tests/unit/engines/test_active_read.py
index 2a7640b..c6bb5b3 100644
--- a/tests/unit/engines/test_active_read.py
+++ b/tests/unit/engines/test_active_read.py
@@ -25,7 +25,7 @@ def make_dv(value=42.0, status='Good', source_ts=None, server_ts=None):
     server_ts = server_ts or source_ts
     return ua.DataValue(
         ua.Variant(value),
-        StatusCode_=ua.StatusCode(getattr(ua.StatusCodes, status)),
+        StatusCode=ua.StatusCode(getattr(ua.StatusCodes, status)),
         SourceTimestamp=source_ts,
         ServerTimestamp=server_ts,
     )
diff --git a/tests/unit/engines/test_write.py b/tests/unit/engines/test_write.py
index 6fc1963..ad54c30 100644
--- a/tests/unit/engines/test_write.py
+++ b/tests/unit/engines/test_write.py
@@ -108,8 +108,8 @@ async def test_write_defaults_carry_statuscode_and_timestamp():
     await eng.write(base_cmd())
 
     dv = node.write_value.await_args.args[0]
-    assert dv.StatusCode_ is not None
-    assert dv.StatusCode_.is_good()
+    assert dv.StatusCode is not None
+    assert dv.StatusCode.is_good()
     assert dv.SourceTimestamp == datetime.fromisoformat('2026-07-13T12:00:00Z')
 
 
@@ -122,7 +122,7 @@ async def test_write_engine_flags_off_omit_statuscode_and_timestamp():
     await eng.write(base_cmd())
 
     dv = node.write_value.await_args.args[0]
-    assert dv.StatusCode_ is None
+    assert dv.StatusCode is None
     assert dv.SourceTimestamp is None
 
 
@@ -137,7 +137,7 @@ async def test_per_message_flag_override_disables_timestamp():
 
     dv = node.write_value.await_args.args[0]
     assert dv.SourceTimestamp is None
-    assert dv.StatusCode_ is not None  # write_quality untouched, stays on
+    assert dv.StatusCode is not None  # write_quality untouched, stays on
 
 
 @pytest.mark.asyncio