diff --git a/klippy/extras/bus.py b/klippy/extras/bus.py
index 4490efe4..66b8330e 100644
--- a/klippy/extras/bus.py
+++ b/klippy/extras/bus.py
@@ -182,6 +182,7 @@ class MCU_I2C:
         self.i2c_write_cmd = self.i2c_read_cmd = None
         printer = self.mcu.get_printer()
         printer.register_event_handler("klippy:connect", self._handle_connect)
+        self._debugoutput = printer.get_start_args().get('debugoutput')
         # backward support i2c_write inside the init section
         self._to_write = []
     def _handle_connect(self):
@@ -216,8 +217,12 @@ class MCU_I2C:
         if self.i2c_write_cmd is None:
             self._to_write.append(data)
             return
-        self.i2c_write_cmd.send([self.oid, data],
-                                minclock=minclock, reqclock=reqclock)
+        if self._debugoutput is not None:
+            self.i2c_write_cmd.send([self.oid, data],
+                                    minclock=minclock, reqclock=reqclock)
+            return
+        self.i2c_write_cmd.send_wait_ack([self.oid, data],
+                                         minclock=minclock, reqclock=reqclock)
     def i2c_write_wait_ack(self, data, minclock=0, reqclock=0):
         self.i2c_write_cmd.send_wait_ack([self.oid, data],
                                 minclock=minclock, reqclock=reqclock)