diff --git a/TrafficCapture/captureOffloader/src/main/java/org/opensearch/migrations/trafficcapture/StreamChannelConnectionCaptureSerializer.java b/TrafficCapture/captureOffloader/src/main/java/org/opensearch/migrations/trafficcapture/StreamChannelConnectionCaptureSerializer.java
index b7a82c8a12..8f9ee1f5e6 100644
--- a/TrafficCapture/captureOffloader/src/main/java/org/opensearch/migrations/trafficcapture/StreamChannelConnectionCaptureSerializer.java
+++ b/TrafficCapture/captureOffloader/src/main/java/org/opensearch/migrations/trafficcapture/StreamChannelConnectionCaptureSerializer.java
@@ -18,6 +18,8 @@
 import org.opensearch.migrations.trafficcapture.protos.TrafficStream;
 import org.opensearch.migrations.trafficcapture.protos.WriteObservation;
 import org.opensearch.migrations.trafficcapture.protos.WriteSegmentObservation;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.net.SocketAddress;
@@ -60,9 +62,10 @@
  * }
  * </pre>
  */
-@Slf4j
 public class StreamChannelConnectionCaptureSerializer<T> implements IChannelConnectionCaptureSerializer<T> {
 
+    private final org.slf4j.Logger log;
+
     private static final int MAX_ID_SIZE = 100;
 
     private boolean readObservationsAreWaitingForEom;
@@ -79,6 +82,15 @@ public class StreamChannelConnectionCaptureSerializer<T> implements IChannelConn
 
     public StreamChannelConnectionCaptureSerializer(String nodeId, String connectionId,
                                                     @NonNull StreamLifecycleManager<T> streamLifecycleManager) {
+        this(nodeId, connectionId, streamLifecycleManager, LoggerFactory.getLogger(StreamChannelConnectionCaptureSerializer.class));
+    }
+
+
+    // Exposed for testing
+    public StreamChannelConnectionCaptureSerializer(String nodeId, String connectionId,
+                                                    StreamLifecycleManager<T> streamLifecycleManager,
+                                                    Logger log) {
+        this.log = log;
         this.streamManager = streamLifecycleManager;
         assert (nodeId == null ? 0 : CodedOutputStream.computeStringSize(TrafficStream.NODEID_FIELD_NUMBER, nodeId)) +
                 CodedOutputStream.computeStringSize(TrafficStream.CONNECTIONID_FIELD_NUMBER, connectionId)
diff --git a/TrafficCapture/captureOffloader/src/test/java/org/opensearch/migrations/trafficcapture/StreamChannelConnectionCaptureSerializerTest.java b/TrafficCapture/captureOffloader/src/test/java/org/opensearch/migrations/trafficcapture/StreamChannelConnectionCaptureSerializerTest.java
index 172205482a..6fc0d75b36 100644
--- a/TrafficCapture/captureOffloader/src/test/java/org/opensearch/migrations/trafficcapture/StreamChannelConnectionCaptureSerializerTest.java
+++ b/TrafficCapture/captureOffloader/src/test/java/org/opensearch/migrations/trafficcapture/StreamChannelConnectionCaptureSerializerTest.java
@@ -1,6 +1,7 @@
 package org.opensearch.migrations.trafficcapture;
 
 import com.google.protobuf.ByteString;
+import com.google.protobuf.CodedOutputStream;
 import com.google.protobuf.Timestamp;
 import io.netty.buffer.Unpooled;
 import lombok.AllArgsConstructor;
@@ -8,6 +9,8 @@
 import lombok.extern.slf4j.Slf4j;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentMatchers;
+import org.mockito.Mockito;
 import org.opensearch.migrations.trafficcapture.protos.CloseObservation;
 import org.opensearch.migrations.trafficcapture.protos.ConnectionExceptionObservation;
 import org.opensearch.migrations.trafficcapture.protos.EndOfMessageIndication;
@@ -16,6 +19,7 @@
 import org.opensearch.migrations.trafficcapture.protos.TrafficObservation;
 import org.opensearch.migrations.trafficcapture.protos.TrafficStream;
 import org.opensearch.migrations.trafficcapture.protos.WriteObservation;
+import org.slf4j.Logger;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
@@ -349,6 +353,32 @@ public void testInitializationWithRealIds() {
                 new StreamManager(getEstimatedTrafficStreamByteSize(0, 0), outputBuffersCreated));
     }
 
+    @Test
+    public void testOutputStreamReportsIncorrectSpaceLeft_thenObservationSizeSanityCheckLogAppears() throws IOException {
+        Logger mockLogger = Mockito.mock(Logger.class);
+
+        StreamManager mockStreamManager = Mockito.mock(StreamManager.class);
+        CodedOutputStreamHolder mockHolder = Mockito.mock(CodedOutputStreamHolder.class);
+        CodedOutputStream mockOutputStream = Mockito.mock(CodedOutputStream.class);
+
+        Mockito.when(mockStreamManager.createStream()).thenReturn(mockHolder);
+        Mockito.when(mockHolder.getOutputStream()).thenReturn(mockOutputStream);
+        Mockito.when(mockOutputStream.spaceLeft()).thenReturn(5);
+        var serializer = new StreamChannelConnectionCaptureSerializer<>(TEST_NODE_ID_STRING, TEST_TRAFFIC_STREAM_ID_STRING,
+                mockStreamManager, mockLogger);
+        var bb = Unpooled.buffer(getEstimatedTrafficStreamByteSize(1, 0));
+        serializer.addWriteEvent(Instant.now(), bb);
+        serializer.flushCommitAndResetStream(true);
+        bb.release();
+
+        Mockito.verify(mockLogger, Mockito.times(1)).warn(
+                ArgumentMatchers.eq("Writing a substream (capture type: {}) for Traffic Stream: {} left {} bytes in the CodedOutputStream but we calculated at least {} bytes remaining, this should be investigated"),
+                ArgumentMatchers.any(int.class),
+                ArgumentMatchers.any(String.class),
+                ArgumentMatchers.any(int.class),
+                ArgumentMatchers.any(int.class));
+    }
+
     @AllArgsConstructor
     static class StreamManager extends OrderedStreamLifecyleManager<Void> {
         int bufferSize;