diff --git a/include/ModemManager-errors.h b/include/ModemManager-errors.h
index 572b8a00..1d397f10 100644
--- a/include/ModemManager-errors.h
+++ b/include/ModemManager-errors.h
@@ -521,6 +521,7 @@ typedef enum { /*< underscore_name=mm_connection_error >*/
  * @MM_SERIAL_ERROR_NOT_OPEN: The serial port is not open.
  * @MM_SERIAL_ERROR_PARSE_FAILED: The serial port specific parsing failed.
  * @MM_SERIAL_ERROR_FRAME_NOT_FOUND: The serial port reported that the frame marker wasn't found (e.g. for QCDM). Since 1.6.
+ * @MM_SERIAL_ERROR_SEND_TIMEOUT: Could not write once again to the serial device.
  *
  * Serial errors that may be reported by ModemManager.
  *
@@ -536,6 +537,7 @@ typedef enum { /*< underscore_name=mm_serial_error >*/
     MM_SERIAL_ERROR_NOT_OPEN              = 6, /*< nick=NotOpen            >*/
     MM_SERIAL_ERROR_PARSE_FAILED          = 7, /*< nick=ParseFailed        >*/
     MM_SERIAL_ERROR_FRAME_NOT_FOUND       = 8, /*< nick=FrameNotFound      >*/
+    MM_SERIAL_ERROR_SEND_TIMEOUT          = 9, /*< nick=SendTimeout        >*/
 } MMSerialError;
 
 /**
diff --git a/src/mm-error-helpers.c b/src/mm-error-helpers.c
index 75598c46..6eb65d18 100644
--- a/src/mm-error-helpers.c
+++ b/src/mm-error-helpers.c
@@ -329,6 +329,7 @@ static const gchar *serial_error_messages[] = {
     [MM_SERIAL_ERROR_NOT_OPEN]              = "Not open",
     [MM_SERIAL_ERROR_PARSE_FAILED]          = "Parse failed",
     [MM_SERIAL_ERROR_FRAME_NOT_FOUND]       = "Frame not found",
+    [MM_SERIAL_ERROR_SEND_TIMEOUT]          = "Send timeout",
 };
 
 static const gchar *
diff --git a/src/mm-port-probe-at.c b/src/mm-port-probe-at.c
index 4505fc76..c9832b6c 100644
--- a/src/mm-port-probe-at.c
+++ b/src/mm-port-probe-at.c
@@ -47,7 +47,10 @@ mm_port_probe_response_processor_is_at (const gchar *command,
                              MM_SERIAL_ERROR_RESPONSE_TIMEOUT) ||
             g_error_matches (error,
                              MM_SERIAL_ERROR,
-                             MM_SERIAL_ERROR_SEND_FAILED)) {
+                             MM_SERIAL_ERROR_SEND_FAILED) ||
+            g_error_matches (error,
+                             MM_SERIAL_ERROR,
+                             MM_SERIAL_ERROR_SEND_TIMEOUT)) {
             return FALSE;
         }
 
diff --git a/src/mm-port-serial.c b/src/mm-port-serial.c
index d1976972..f520ff83 100644
--- a/src/mm-port-serial.c
+++ b/src/mm-port-serial.c
@@ -596,7 +596,7 @@ port_serial_process_command (MMPortSerial *self,
                 self->priv->n_consecutive_timeouts++;
                 g_signal_emit_by_name (self, MM_PORT_SIGNAL_TIMED_OUT, self->priv->n_consecutive_timeouts);
 
-                g_set_error (error, MM_SERIAL_ERROR, MM_SERIAL_ERROR_SEND_FAILED,
+                g_set_error (error, MM_SERIAL_ERROR, MM_SERIAL_ERROR_SEND_TIMEOUT,
                              "Sending command failed: '%s'", g_strerror (errno));
                 return FALSE;
             }
@@ -631,7 +631,7 @@ port_serial_process_command (MMPortSerial *self,
                 /* If we reach the limit of EAGAIN errors, treat as a timeout error. */
                 self->priv->n_consecutive_timeouts++;
                 g_signal_emit_by_name (self, MM_PORT_SIGNAL_TIMED_OUT, self->priv->n_consecutive_timeouts);
-                g_set_error (error, MM_SERIAL_ERROR, MM_SERIAL_ERROR_SEND_FAILED,
+                g_set_error (error, MM_SERIAL_ERROR, MM_SERIAL_ERROR_SEND_TIMEOUT,
                              "Sending command failed: '%s'", g_strerror (errno));
                 return FALSE;
             }