diff --git a/action_processor.h b/action_processor.h
index 9bc4ef2..2618c39 100644
--- a/action_processor.h
+++ b/action_processor.h
@@ -38,6 +38,12 @@
   kActionCodeDownloadPayloadVerificationError = 12,
   kActionCodeDownloadAppliedUpdateVerificationError = 13,
   kActionCodeDownloadWriteError = 14,
+  kActionCodeOmahaRequestEmptyResponseError = 200,
+  kActionCodeOmahaRequestXMLParseError = 201,
+  kActionCodeOmahaRequestNoUpdateCheckNode = 202,
+  kActionCodeOmahaRequestNoUpdateCheckStatus = 203,
+  kActionCodeOmahaRequestBadUpdateCheckStatus = 204,
+  kActionCodeOmahaRequestHTTPResponseBase = 2000,  // + HTTP response code
 };
 
 class AbstractAction;
diff --git a/mock_http_fetcher.cc b/mock_http_fetcher.cc
index 2e11865..eec550f 100644
--- a/mock_http_fetcher.cc
+++ b/mock_http_fetcher.cc
@@ -17,7 +17,11 @@
 }
 
 void MockHttpFetcher::BeginTransfer(const std::string& url) {
-  http_response_code_ = 0;
+  if (fail_transfer_ || data_.empty()) {
+    // No data to send, just notify of completion..
+    SignalTransferComplete();
+    return;
+  }
   if (sent_size_ < data_.size())
     SendData(true);
 }
@@ -26,6 +30,11 @@
 // and it needs to be deleted by the caller. If timeout_source_ is NULL
 // when this function is called, this function will always return true.
 bool MockHttpFetcher::SendData(bool skip_delivery) {
+  if (fail_transfer_) {
+    SignalTransferComplete();
+    return timeout_source_;
+  }
+
   CHECK_LT(sent_size_, data_.size());
   if (!skip_delivery) {
     const size_t chunk_size = min(kMockHttpFetcherChunkSize,
@@ -36,8 +45,7 @@
     CHECK_LE(sent_size_, data_.size());
     if (sent_size_ == data_.size()) {
       // We've sent all the data. Notify of success.
-      http_response_code_ = 200;
-      delegate_->TransferComplete(this, true);
+      SignalTransferComplete();
     }
   }
 
@@ -101,4 +109,18 @@
   }
 }
 
+void MockHttpFetcher::FailTransfer(int http_response_code) {
+  fail_transfer_ = true;
+  http_response_code_ = http_response_code;
+}
+
+void MockHttpFetcher::SignalTransferComplete() {
+  // If the transfer has been failed, the HTTP response code should be set
+  // already.
+  if (!fail_transfer_) {
+    http_response_code_ = 200;
+  }
+  delegate_->TransferComplete(this, !fail_transfer_);
+}
+
 }  // namespace chromeos_update_engine
diff --git a/mock_http_fetcher.h b/mock_http_fetcher.h
index f0830f0..dfe61a7 100644
--- a/mock_http_fetcher.h
+++ b/mock_http_fetcher.h
@@ -27,7 +27,11 @@
   // The data passed in here is copied and then passed to the delegate after
   // the transfer begins.
   MockHttpFetcher(const char* data, size_t size)
-      : sent_size_(0), timeout_source_(NULL), timout_tag_(0), paused_(false) {
+      : sent_size_(0),
+        timeout_source_(NULL),
+        timout_tag_(0),
+        paused_(false),
+        fail_transfer_(false) {
     data_.insert(data_.end(), data, data + size);
   }
 
@@ -55,7 +59,7 @@
   virtual void Unpause();
 
   // Fail the transfer. This simulates a network failure.
-  void FailTransfer();
+  void FailTransfer(int http_response_code);
 
   const std::vector<char>& post_data() const {
     return post_data_;
@@ -76,6 +80,10 @@
     return reinterpret_cast<MockHttpFetcher*>(data)->TimeoutCallback();
   }
 
+  // Sets the HTTP response code and signals to the delegate that the transfer
+  // is complete.
+  void SignalTransferComplete();
+
   // A full copy of the data we'll return to the delegate
   std::vector<char> data_;
 
@@ -92,6 +100,9 @@
   // True iff the fetcher is paused.
   bool paused_;
 
+  // Set to true if the transfer should fail.
+  bool fail_transfer_;
+
   DISALLOW_COPY_AND_ASSIGN(MockHttpFetcher);
 };
 
diff --git a/omaha_request_action.cc b/omaha_request_action.cc
index ecee25e..5166315 100644
--- a/omaha_request_action.cc
+++ b/omaha_request_action.cc
@@ -329,6 +329,13 @@
 
   if (!successful) {
     LOG(ERROR) << "Omaha request network transfer failed.";
+    int code = GetHTTPResponseCode();
+    // Makes sure we send sane error values.
+    if (code < 0 || code >= 1000) {
+      code = 999;
+    }
+    completer.set_code(static_cast<ActionExitCode>(
+        kActionCodeOmahaRequestHTTPResponseBase + code));
     return;
   }
   if (!HasOutputPipe()) {
@@ -343,6 +350,9 @@
       xmlParseMemory(&response_buffer_[0], response_buffer_.size()));
   if (!doc.get()) {
     LOG(ERROR) << "Omaha response not valid XML";
+    completer.set_code(response_buffer_.empty() ?
+                       kActionCodeOmahaRequestEmptyResponseError :
+                       kActionCodeOmahaRequestXMLParseError);
     return;
   }
 
@@ -366,6 +376,7 @@
                                ConstXMLStr(kNamespace),
                                ConstXMLStr(kNsUrl)));
   if (!xpath_nodeset.get()) {
+    completer.set_code(kActionCodeOmahaRequestNoUpdateCheckNode);
     return;
   }
   xmlNodeSet* nodeset = xpath_nodeset->nodesetval;
@@ -376,6 +387,7 @@
   // get status
   if (!xmlHasProp(updatecheck_node, ConstXMLStr("status"))) {
     LOG(ERROR) << "Response missing status";
+    completer.set_code(kActionCodeOmahaRequestNoUpdateCheckStatus);
     return;
   }
 
@@ -393,6 +405,7 @@
 
   if (status != "ok") {
     LOG(ERROR) << "Unknown status: " << status;
+    completer.set_code(kActionCodeOmahaRequestBadUpdateCheckStatus);
     return;
   }
 
diff --git a/omaha_request_action_unittest.cc b/omaha_request_action_unittest.cc
index f822357..2501d2d 100755
--- a/omaha_request_action_unittest.cc
+++ b/omaha_request_action_unittest.cc
@@ -145,19 +145,24 @@
 };
 
 // Returns true iff an output response was obtained from the
-// OmahaRequestAction. |prefs| may be NULL, in which case a local
-// PrefsMock is used. out_response may be NULL.  out_post_data may be
-// null; if non-null, the post-data received by the mock HttpFetcher
-// is returned.
+// OmahaRequestAction. |prefs| may be NULL, in which case a local PrefsMock is
+// used. out_response may be NULL. If |fail_http_response_code| is
+// non-negative, the transfer will fail with that code. out_post_data may be
+// null; if non-null, the post-data received by the mock HttpFetcher is
+// returned.
 bool TestUpdateCheck(PrefsInterface* prefs,
                      const OmahaRequestParams& params,
                      const string& http_response,
+                     int fail_http_response_code,
                      ActionExitCode expected_code,
                      OmahaResponse* out_response,
                      vector<char>* out_post_data) {
   GMainLoop* loop = g_main_loop_new(g_main_context_default(), FALSE);
   MockHttpFetcher* fetcher = new MockHttpFetcher(http_response.data(),
                                                  http_response.size());
+  if (fail_http_response_code >= 0) {
+    fetcher->FailTransfer(fail_http_response_code);
+  }
   PrefsMock local_prefs;
   OmahaRequestAction action(prefs ? prefs : &local_prefs,
                             params,
@@ -216,6 +221,7 @@
       TestUpdateCheck(NULL,  // prefs
                       kDefaultTestParams,
                       GetNoUpdateResponse(OmahaRequestParams::kAppId),
+                      -1,
                       kActionCodeSuccess,
                       &response,
                       NULL));
@@ -236,6 +242,7 @@
                                         "false",  // needs admin
                                         "123",  // size
                                         "20101020"),  // deadline
+                      -1,
                       kActionCodeSuccess,
                       &response,
                       NULL));
@@ -278,7 +285,21 @@
       TestUpdateCheck(NULL,  // prefs
                       kDefaultTestParams,
                       "invalid xml>",
-                      kActionCodeError,
+                      -1,
+                      kActionCodeOmahaRequestXMLParseError,
+                      &response,
+                      NULL));
+  EXPECT_FALSE(response.update_exists);
+}
+
+TEST(OmahaRequestActionTest, EmptyResponseTest) {
+  OmahaResponse response;
+  ASSERT_FALSE(
+      TestUpdateCheck(NULL,  // prefs
+                      kDefaultTestParams,
+                      "",
+                      -1,
+                      kActionCodeOmahaRequestEmptyResponseError,
                       &response,
                       NULL));
   EXPECT_FALSE(response.update_exists);
@@ -293,7 +314,8 @@
       "xmlns=\"http://www.google.com/update2/response\" protocol=\"2.0\"><app "
       "appid=\"foo\" status=\"ok\"><ping "
       "status=\"ok\"/><updatecheck/></app></gupdate>",
-      kActionCodeError,
+      -1,
+      kActionCodeOmahaRequestNoUpdateCheckStatus,
       &response,
       NULL));
   EXPECT_FALSE(response.update_exists);
@@ -308,7 +330,8 @@
       "xmlns=\"http://www.google.com/update2/response\" protocol=\"2.0\"><app "
       "appid=\"foo\" status=\"ok\"><ping "
       "status=\"ok\"/><updatecheck status=\"foo\"/></app></gupdate>",
-      kActionCodeError,
+      -1,
+      kActionCodeOmahaRequestBadUpdateCheckStatus,
       &response,
       NULL));
   EXPECT_FALSE(response.update_exists);
@@ -323,7 +346,8 @@
       "xmlns=\"http://www.google.com/update2/response\" protocol=\"2.0\"><app "
       "appid=\"foo\" status=\"ok\"><ping "
       "status=\"ok\"/></app></gupdate>",
-      kActionCodeError,
+      -1,
+      kActionCodeOmahaRequestNoUpdateCheckNode,
       &response,
       NULL));
   EXPECT_FALSE(response.update_exists);
@@ -347,6 +371,7 @@
                               "sha256=\"HASH1234=\" needsadmin=\"true\" "
                               "size=\"123\" "
                               "status=\"ok\"/></app></gupdate>",
+                              -1,
                               kActionCodeSuccess,
                               &response,
                               NULL));
@@ -426,7 +451,8 @@
       TestUpdateCheck(NULL,  // prefs
                       params,
                       "invalid xml>",
-                      kActionCodeError,
+                      -1,
+                      kActionCodeOmahaRequestXMLParseError,
                       &response,
                       &post_data));
   // convert post_data to string
@@ -455,6 +481,7 @@
                                         "false",  // needs admin
                                         "123",  // size
                                         "&lt;20110101"),  // deadline
+                      -1,
                       kActionCodeSuccess,
                       &response,
                       NULL));
@@ -479,6 +506,7 @@
                                         // overflows int32:
                                         "123123123123123",  // size
                                         "deadline"),
+                      -1,
                       kActionCodeSuccess,
                       &response,
                       NULL));
@@ -491,7 +519,8 @@
   ASSERT_FALSE(TestUpdateCheck(NULL,  // prefs
                                kDefaultTestParams,
                                "invalid xml>",
-                               kActionCodeError,
+                               -1,
+                               kActionCodeOmahaRequestXMLParseError,
                                NULL,  // response
                                &post_data));
   // convert post_data to string
@@ -600,7 +629,8 @@
     ASSERT_FALSE(TestUpdateCheck(NULL,  // prefs
                                  params,
                                  "invalid xml>",
-                                 kActionCodeError,
+                                 -1,
+                                 kActionCodeOmahaRequestXMLParseError,
                                  NULL,
                                  &post_data));
     // convert post_data to string
@@ -646,6 +676,7 @@
       TestUpdateCheck(&prefs,
                       kDefaultTestParams,
                       GetNoUpdateResponse(OmahaRequestParams::kAppId),
+                      -1,
                       kActionCodeSuccess,
                       NULL,
                       &post_data));
@@ -667,6 +698,7 @@
       TestUpdateCheck(&prefs,
                       kDefaultTestParams,
                       GetNoUpdateResponse(OmahaRequestParams::kAppId),
+                      -1,
                       kActionCodeSuccess,
                       NULL,
                       &post_data));
@@ -688,6 +720,7 @@
       TestUpdateCheck(&prefs,
                       kDefaultTestParams,
                       GetNoUpdateResponse(OmahaRequestParams::kAppId),
+                      -1,
                       kActionCodeSuccess,
                       NULL,
                       &post_data));
@@ -710,6 +743,7 @@
       TestUpdateCheck(&prefs,
                       kDefaultTestParams,
                       GetNoUpdateResponse(OmahaRequestParams::kAppId),
+                      -1,
                       kActionCodeSuccess,
                       NULL,
                       &post_data));
@@ -738,6 +772,7 @@
                       "protocol=\"2.0\"><daystart elapsed_seconds=\"100\"/>"
                       "<app appid=\"foo\" status=\"ok\"><ping status=\"ok\"/>"
                       "<updatecheck status=\"noupdate\"/></app></gupdate>",
+                      -1,
                       kActionCodeSuccess,
                       NULL,
                       &post_data));
@@ -769,6 +804,7 @@
                       "protocol=\"2.0\"><daystart elapsed_seconds=\"200\"/>"
                       "<app appid=\"foo\" status=\"ok\"><ping status=\"ok\"/>"
                       "<updatecheck status=\"noupdate\"/></app></gupdate>",
+                      -1,
                       kActionCodeSuccess,
                       NULL,
                       NULL));
@@ -786,6 +822,7 @@
                       "protocol=\"2.0\"><daystart blah=\"200\"/>"
                       "<app appid=\"foo\" status=\"ok\"><ping status=\"ok\"/>"
                       "<updatecheck status=\"noupdate\"/></app></gupdate>",
+                      -1,
                       kActionCodeSuccess,
                       NULL,
                       NULL));
@@ -803,6 +840,7 @@
                       "protocol=\"2.0\"><daystart elapsed_seconds=\"x\"/>"
                       "<app appid=\"foo\" status=\"ok\"><ping status=\"ok\"/>"
                       "<updatecheck status=\"noupdate\"/></app></gupdate>",
+                      -1,
                       kActionCodeSuccess,
                       NULL,
                       NULL));
@@ -813,7 +851,8 @@
   ASSERT_FALSE(TestUpdateCheck(NULL,  // prefs
                                kDefaultTestParams,
                                "invalid xml>",
-                               kActionCodeError,
+                               -1,
+                               kActionCodeOmahaRequestXMLParseError,
                                NULL,  // response
                                &post_data));
   // convert post_data to string
@@ -822,4 +861,32 @@
   EXPECT_EQ(post_str.find("userid="), string::npos);
 }
 
+TEST(OmahaRequestActionTest, NetworkFailureTest) {
+  OmahaResponse response;
+  ASSERT_FALSE(
+      TestUpdateCheck(NULL,  // prefs
+                      kDefaultTestParams,
+                      "",
+                      501,
+                      static_cast<ActionExitCode>(
+                          kActionCodeOmahaRequestHTTPResponseBase + 501),
+                      &response,
+                      NULL));
+  EXPECT_FALSE(response.update_exists);
+}
+
+TEST(OmahaRequestActionTest, NetworkFailureBadHTTPCodeTest) {
+  OmahaResponse response;
+  ASSERT_FALSE(
+      TestUpdateCheck(NULL,  // prefs
+                      kDefaultTestParams,
+                      "",
+                      1500,
+                      static_cast<ActionExitCode>(
+                          kActionCodeOmahaRequestHTTPResponseBase + 999),
+                      &response,
+                      NULL));
+  EXPECT_FALSE(response.update_exists);
+}
+
 }  // namespace chromeos_update_engine