diff --git a/src_features/signTx/cmd_signTx.c b/src_features/signTx/cmd_signTx.c
index c2d943cea8..ed7552d2e1 100644
--- a/src_features/signTx/cmd_signTx.c
+++ b/src_features/signTx/cmd_signTx.c
@@ -87,11 +87,10 @@ uint16_t handleSign(uint8_t p1,
                 // We have encountered an error while trying to sign a SWAP type transaction
                 // Return dedicated error code and flag an early exit back to Exchange
                 G_swap_response_ready = true;
-                send_swap_error(ERROR_GENERIC, "Wrong mode", NULL);
+                send_swap_error(ERROR_GENERIC, APP_CODE_WRONG_SWAP_MODE, NULL, NULL);
                 return APDU_NO_RESPONSE;
-            } else {
-                return APDU_RESPONSE_INVALID_DATA;
             }
+            return APDU_RESPONSE_INVALID_DATA;
         default:
             PRINTF("Unexpected parser status\n");
             return APDU_RESPONSE_INVALID_DATA;
diff --git a/src_features/signTx/feature_signTx.h b/src_features/signTx/feature_signTx.h
index 223f0936b0..14478d15ab 100644
--- a/src_features/signTx/feature_signTx.h
+++ b/src_features/signTx/feature_signTx.h
@@ -12,6 +12,9 @@
 #define ERROR_CROSSCHAIN_WRONG_METHOD 0x06
 #define ERROR_GENERIC                 0xFF
 
+// App codes for detail.
+typedef enum { APP_CODE_DEFAULT, APP_CODE_WRONG_SWAP_MODE, APP_CODE_NO_STANDARD_UI } app_code_t;
+
 typedef enum {
 
     PLUGIN_UI_INSIDE = 0,
@@ -24,6 +27,6 @@ uint16_t finalizeParsing();
 void ux_approve_tx(bool fromPlugin);
 void start_signature_flow(void);
 
-void send_swap_error(uint8_t error_code, const char *str1, const char *str2);
+void send_swap_error(uint8_t error_code, app_code_t app_code, const char *str1, const char *str2);
 
 #endif  // _SIGN_TX_H_
diff --git a/src_features/signTx/logic_signTx.c b/src_features/signTx/logic_signTx.c
index 4498c36ed3..408b78e299 100644
--- a/src_features/signTx/logic_signTx.c
+++ b/src_features/signTx/logic_signTx.c
@@ -324,12 +324,12 @@ static int strcasecmp_workaround(const char *str1, const char *str2) {
     return 0;
 }
 
-void send_swap_error(uint8_t error_code, const char *str1, const char *str2) {
+void send_swap_error(uint8_t error_code, app_code_t app_code, const char *str1, const char *str2) {
     uint32_t tx = 0;
     PRINTF("APDU_RESPONSE_MODE_CHECK_FAILED: 0x%x\n", error_code);
     // Set RAPDU error codes
     G_io_apdu_buffer[tx++] = error_code;
-    G_io_apdu_buffer[tx++] = 0x00;
+    G_io_apdu_buffer[tx++] = app_code & 0xFF;
     // Set RAPDU error message
     if (str1 != NULL) {
         PRINTF("Expected %s\n", str1);
@@ -486,13 +486,13 @@ __attribute__((noinline)) static uint16_t finalize_parsing_helper(void) {
         // User has just validated a swap but ETH received apdus about a non standard plugin /
         // contract
         if (!g_use_standard_ui) {
-            send_swap_error(ERROR_GENERIC, "No Standard UI", NULL);
+            send_swap_error(ERROR_GENERIC, APP_CODE_NO_STANDARD_UI, NULL, NULL);
             return APDU_NO_RESPONSE;
         }
         // Two success cases: we are in standard mode and no calldata was received
         // We are in crosschain mode and the correct calldata has been received
         if (G_swap_mode != SWAP_MODE_STANDARD && G_swap_mode != SWAP_MODE_CROSSCHAIN_SUCCESS) {
-            send_swap_error(ERROR_CROSSCHAIN_WRONG_MODE, "Wrong swap mode", NULL);
+            send_swap_error(ERROR_CROSSCHAIN_WRONG_MODE, APP_CODE_WRONG_SWAP_MODE, NULL, NULL);
             return APDU_NO_RESPONSE;
         }
     }
@@ -519,7 +519,10 @@ __attribute__((noinline)) static uint16_t finalize_parsing_helper(void) {
         if (G_called_from_swap) {
             // Ensure the values are the same that the ones that have been previously validated
             if (strcasecmp_workaround(strings.common.toAddress, displayBuffer) != 0) {
-                send_swap_error(ERROR_WRONG_DESTINATION, strings.common.toAddress, displayBuffer);
+                send_swap_error(ERROR_WRONG_DESTINATION,
+                                APP_CODE_DEFAULT,
+                                strings.common.toAddress,
+                                displayBuffer);
                 return APDU_NO_RESPONSE;
             }
         } else {
@@ -542,7 +545,10 @@ __attribute__((noinline)) static uint16_t finalize_parsing_helper(void) {
         if (G_called_from_swap) {
             // Ensure the values are the same that the ones that have been previously validated
             if (strcmp(strings.common.fullAmount, displayBuffer) != 0) {
-                send_swap_error(ERROR_WRONG_AMOUNT, strings.common.fullAmount, displayBuffer);
+                send_swap_error(ERROR_WRONG_AMOUNT,
+                                APP_CODE_DEFAULT,
+                                strings.common.fullAmount,
+                                displayBuffer);
                 return APDU_NO_RESPONSE;
             }
         } else {
@@ -562,7 +568,10 @@ __attribute__((noinline)) static uint16_t finalize_parsing_helper(void) {
     if (G_called_from_swap) {
         // Ensure the values are the same that the ones that have been previously validated
         if (strcmp(strings.common.maxFee, displayBuffer) != 0) {
-            send_swap_error(ERROR_WRONG_FEES, strings.common.maxFee, displayBuffer);
+            send_swap_error(ERROR_WRONG_FEES,
+                            APP_CODE_DEFAULT,
+                            strings.common.maxFee,
+                            displayBuffer);
             return APDU_NO_RESPONSE;
         }
     } else {