diff --git a/ironic/api/controllers/v1/node.py b/ironic/api/controllers/v1/node.py
index f176a523f4..65d0c347fa 100644
--- a/ironic/api/controllers/v1/node.py
+++ b/ironic/api/controllers/v1/node.py
@@ -478,7 +478,7 @@ class Node(base.APIBase):
             except exception.ChassisNotFound as e:
                 # Change error code because 404 (NotFound) is inappropriate
                 # response for a POST request to create a Port
-                e.code = http_client.BAD_REQUEST  # BadRequest
+                e.code = http_client.BAD_REQUEST
                 raise e
         elif value == wtypes.Unset:
             self._chassis_uuid = wtypes.Unset
diff --git a/ironic/api/hooks.py b/ironic/api/hooks.py
index 6861ad6aa7..90c1a2f963 100644
--- a/ironic/api/hooks.py
+++ b/ironic/api/hooks.py
@@ -135,6 +135,8 @@ class NoExceptionTracebackHook(hooks.PecanHook):
             return
 
         # Do nothing if there is no error.
+        # Status codes in the range 200 (OK) to 399 (400 = BAD_REQUEST) are not
+        # an error.
         if (http_client.OK <= state.response.status_int <
                 http_client.BAD_REQUEST):
             return
diff --git a/ironic/common/exception.py b/ironic/common/exception.py
index 129bb71ab9..580d955f71 100644
--- a/ironic/common/exception.py
+++ b/ironic/common/exception.py
@@ -443,7 +443,7 @@ class NodeNotLocked(Invalid):
 class NoFreeConductorWorker(TemporaryFailure):
     message = _('Requested action cannot be performed due to lack of free '
                 'conductor workers.')
-    code = http_client.SERVICE_UNAVAILABLE  # Service Unavailable (temporary).
+    code = http_client.SERVICE_UNAVAILABLE
 
 
 class VendorPassthruException(IronicException):