diff --git a/ceilometer/api/controllers/v2.py b/ceilometer/api/controllers/v2.py
index ff231af226..cf65dcc254 100644
--- a/ceilometer/api/controllers/v2.py
+++ b/ceilometer/api/controllers/v2.py
@@ -1298,7 +1298,7 @@ class Alarm(_Base):
                 alarms = list(pecan.request.storage_conn.get_alarms(
                     alarm_id=id, project=project))
                 if not alarms:
-                    raise ClientSideError(_("Alarm %s doesn't exist") % id)
+                    raise EntityNotFound(_('Alarm'), id)
 
         return alarm
 
@@ -1596,7 +1596,9 @@ class AlarmsController(rest.RestController):
         alarms = list(conn.get_alarms(name=data.name,
                                       project=data.project_id))
         if alarms:
-            raise ClientSideError(_("Alarm with that name exists"))
+            raise ClientSideError(
+                _("Alarm with name='%s' exists") % data.name,
+                status_code=409)
 
         try:
             alarm_in = storage.models.Alarm(**change)
@@ -1731,7 +1733,7 @@ def requires_admin(func):
         usr_limit, proj_limit = acl.get_limited_to(pecan.request.headers)
         # If User and Project are None, you have full access.
         if usr_limit and proj_limit:
-            raise ClientSideError(_("Not Authorized"), status_code=403)
+            raise ProjectNotAuthorized(proj_limit)
         return func(*args, **kwargs)
 
     return wrapped
diff --git a/ceilometer/tests/api/v2/test_acl_scenarios.py b/ceilometer/tests/api/v2/test_acl_scenarios.py
index e4db2187c4..0229f9fac5 100644
--- a/ceilometer/tests/api/v2/test_acl_scenarios.py
+++ b/ceilometer/tests/api/v2/test_acl_scenarios.py
@@ -225,6 +225,6 @@ class TestAPIACL(FunctionalTest,
                                    "X-Auth-Token": VALID_TOKEN2,
                                    "X-Project-Id": "project-good"})
         except v2_api.ClientSideError as ex:
-            self.assertEqual(403, ex.code)
+            self.assertEqual(401, ex.code)
         else:
             self.fail()
diff --git a/ceilometer/tests/api/v2/test_alarm_scenarios.py b/ceilometer/tests/api/v2/test_alarm_scenarios.py
index 24df09314c..eec679fa84 100644
--- a/ceilometer/tests/api/v2/test_alarm_scenarios.py
+++ b/ceilometer/tests/api/v2/test_alarm_scenarios.py
@@ -438,6 +438,35 @@ class TestAlarms(FunctionalTest,
         else:
             self.fail("Alarm not found")
 
+    def test_post_conflict(self):
+        json = {
+            'enabled': False,
+            'name': 'added_alarm',
+            'state': 'ok',
+            'type': 'threshold',
+            'ok_actions': ['http://something/ok'],
+            'alarm_actions': ['http://something/alarm'],
+            'insufficient_data_actions': ['http://something/no'],
+            'repeat_actions': True,
+            'threshold_rule': {
+                'meter_name': 'ameter',
+                'query': [{'field': 'metadata.field',
+                           'op': 'eq',
+                           'value': '5',
+                           'type': 'string'}],
+                'comparison_operator': 'le',
+                'statistic': 'count',
+                'threshold': 50,
+                'evaluation_periods': '3',
+                'period': '180',
+            }
+        }
+
+        self.post_json('/alarms', params=json, status=201,
+                       headers=self.auth_headers)
+        self.post_json('/alarms', params=json, status=409,
+                       headers=self.auth_headers)
+
     def _do_test_post_alarm(self, exclude_outliers=None):
         json = {
             'enabled': False,
@@ -679,11 +708,11 @@ class TestAlarms(FunctionalTest,
         }
         an_other_user_auth = {'X-User-Id': str(uuid.uuid4()),
                               'X-Project-Id': str(uuid.uuid4())}
-        resp = self.post_json('/alarms', params=json, status=400,
+        resp = self.post_json('/alarms', params=json, status=404,
                               headers=an_other_user_auth)
-        self.assertEqual(jsonutils.loads(resp.body)['error_message']
-                         ['faultstring'],
-                         "Alarm a doesn't exist")
+        self.assertEqual("Alarm a Not Found",
+                         jsonutils.loads(resp.body)['error_message']
+                         ['faultstring'])
 
     def test_post_combination_alarm_as_admin_on_behalf_of_an_other_user(self):
         """Test that post a combination alarm as admin on behalf of an other
@@ -710,11 +739,11 @@ class TestAlarms(FunctionalTest,
         headers = {}
         headers.update(self.auth_headers)
         headers['X-Roles'] = 'admin'
-        resp = self.post_json('/alarms', params=json, status=400,
+        resp = self.post_json('/alarms', params=json, status=404,
                               headers=headers)
-        self.assertEqual(jsonutils.loads(resp.body)['error_message']
-                         ['faultstring'],
-                         "Alarm a doesn't exist")
+        self.assertEqual("Alarm a Not Found",
+                         jsonutils.loads(resp.body)['error_message']
+                         ['faultstring'])
 
     def test_post_combination_alarm_as_admin_success_owner_unset(self):
         self._do_post_combination_alarm_as_admin_success(False)
@@ -780,7 +809,7 @@ class TestAlarms(FunctionalTest,
                 'operator': 'and',
             }
         }
-        self.post_json('/alarms', params=json, status=400,
+        self.post_json('/alarms', params=json, status=404,
                        headers=self.auth_headers)
         alarms = list(self.conn.get_alarms(enabled=False))
         self.assertEqual(0, len(alarms))