IMPORTANT: This file is only for use with the models identified. Not all models are sold in all countries.

This information is for the following models:

  • MEX-N4200BT
  • MXS-N4216BT

About this download

Benefits and improvements

This utility updates the firmware of your Bluetooth® Audio System to version M 12 / S 34 and resolves an issue where the sound is distorted when the High-Pass Filter (HPF) is switched.

Benefits provided by previous updates and included in version M 12 / S 34:

  • Resolves an issue where the sound during a call is not output through the speakers when the Bluetooth RINGTONE is set to 1.

System Requirements

Operating Systems

  • System Software

File Info

File Name


File Version

  • M 12 / S 34

File Size

  • 0.73 MB

Release Date

  • 08-29-2018

Download & Install

STEP 1. Download and transfer the Update Files to Your USB Storage Device

  1. Connect a compatible USB storage device to your computer.
    Note: The USB storage device must be formatted for FAT16 orFAT32 file systems.
  2. Ensure your computer is connected to the Internet.
  3. Download the file to a temporary or download directory (please notethis directory for reference) on your computer.
  4. Go to the directory where the file was downloaded and double-click the file, and then click Extract all.
  5. In the Extract Compressed (Zipped) Folders screen, make sure the box next to Show extracted files when complete is checked, then click the Extract button.
  6. In the MEXN4200BT_M12S34 folder, copy the MEXN4200BT_M12S34.U88 file to the USB storage device:
    • Apple® Mac OS X® operating systems: Drag and drop the MEXN4200BT_M12S34.U88 file to the root directory of the USB device.
    • For Microsoft® Windows® operating systems: Right-click the MEXN4200BT_M12S34.U88 file, click Send To..., and then click the drive letter representing your USB device
    • The root directory is the drive itself. Just move the MEXN4200BT_M12S34.U88 file directly to the drive and don't specify a folder.
    • The update will not perform if the MEXN4200BT_M12S34.U88 file is not copied to the root directory of the USB device or if the name of the folder is modified.
  7. Remove the USB storage device from your computer.
  8. Continue to the next section

STEP 2. Perform the Firmware Update

  1. Turn on the Bluetooth Audio System.
  2. Press and hold the SOURCE button (SRC is printed on the button) for 1second to turn the source off and display the clock.
  3. Press MENU button.
  4. Turn the control dial to display GENERAL, and then press the ENTERbutton.
  5. Turn the control dial to display SET FIRMWARE, and then press the ENTER button.
  6. Turn the control dial to display FW UPDATE, and then press the ENTERbutton.
  7. Turn the control dial to display FW UPDATE-YES, and then press the ENTER button.
  8. When the message INSERT USB is displayed, connect the USB storage device to the USB port on thefront panel of the Bluetooth Audio System.
  9. The update process will begin and should finish in approximately 2 minutes.
    Note: When the update process is finished, the unit will restart automatically.
  10. Check the current firmware version to confirm that the update has successfully installed.
    • If the version number is M 12 / S 34, the firmware update was successful.
    • If the version number isn't M 12 / S 34, delete the MEXN4200BT_M12S34.U88 file from the USB storage device (or use a different USB device) and thendownload and install the update again.