What’s an MCU? Which MCU do I have? What’s the difference between MCU & FSD? Why does my car not get the latest software features? How do I speed up my MCU?

Last modified: 08/09/2020
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MCU stands for Media Control Unit, it’s the main computer in Tesla Model S and X vehicles and includes the touchscreen, processors (brain), RAM (short term memory), non-volatile memory (longterm memory), the audio subsystem, 5 amplifiers, WiFi, Cellular, Bluetooth, GPS, the Ethernet bridge, multiple CAN bus communications, the LIN bus, USB ports and many more. and the main computer for the car (excluding AutoPilot) there have been to date two versions of this in Tesla cars:

  • MCU1 – from 2012 to early 2018 (March-May) which is based on an Nvidia Tegra 3 chipset
    • Prone to eMMC chip failure due to the 8GB eMMC chip and excessive software writing to the chip
    • Prone to slowing down over time and temporary glitches
    • The technology didn’t improve much between 2012-2018
    • The software has improved various aspects of the MCU over the years, most notably in 2018 with a browser update
    • Tesla now offers a refurbished version of the MCU1 computer with an upgraded 64GB eMMC chip
  • MCU2 – from 2018 (March-May) onwards is an upgraded version featuring:
    • Faster CPU based on an Intel Atom E8000 series CPU (x86_64), results in smoother and faster operation across the whole experience
    • The browser is built on Google’s Chromium platform
    • 64GB eMMC Chip (Vs 8GB on MCU1)
    • WiFi Support for 5 GHz band
    • External Bluetooth Antenna
    • Enhanced Driving Visualization for owners with Full Self-Driving Capability Computer
    • The ability to record from all cameras for DashCam and Sentry Mode for cars with the Full Self-Driving Computer
    • Many of the Fun Games and Video Streaming capabilities

How do I tell which MCU I have?

MCU2 was fitted in “early March 2018”, in terms of UK deliveries that’s probably May-ish 2018 but to be 100% sure you can do the following:

  1. Reboot the display using the control wheels on the steering wheel, hold both in for 10 or more seconds, if both displays reboot, then the vehicle is equipped with MCU2, if only one reboots then you have MCU1
  2. If you have Netflix/Cuphead game you have MCU2
  3. You can also visit https://teslatap.com/mcu (on the in-car browser, obviously!) to find out which one you have.

Can I upgrade my MCU1 to MCU2?

UPDATE SEPTEMBER 2020: MCU1 -> MCU2 upgrades now available in the UK for £2000 + VAT, book via your app.

Yes, owners of all Model S and Model X vehicles with AP2.x and Tegra MCU are now eligible to book for MCU upgrades.
Note that upgrades for pre-AP or AP1 models are not available in the UK yet and there are no timescales for this procedure available.
MCU upgrade is a voluntary procedure provided on a customer-pay basis. The cost of the upgrade is GBP2,000 + VAT.
All customers are welcome to schedule their appointments for this procedure as per normal via the Tesla App. The Tesla team will review and reconfirm eligibility as a part of the appointment preparation process.

Can I speed up my MCU?

Whilst most of these won’t clog up that much data, when combined it can (although it shouldn’t) slow down your MCU1, so try the following (one by one and between each one leave it a day or two and do a reboot/reset):

  • Try a reboot first – Sometimes this can resolve it
  • Clear the trip logs/computers/meters
  • Clear the previous destination history on the navigation (annoyingly you have to do them one by one by swiping on each one)
  • Remove USB devices (especially if you have music files stored on them)
  • See if the browser is on a complex website (e.g. with lots of graphics)
  • Simplify any Spotify playlists
  • Disconnect your phone’s bluetooth, storing lots of contacts in the car can clog up space on the MCU
  • Switch off traffic indication on the map via the traffic light icon (big improvement)
  • Switch to “North Up” map display (tangible improvement)
  • Reporting the issue with Tesla (& request a software update)
  • See if something on the above devices is corrupt (e.g. a phone contact or music file)
  • Do a factory reset (not ideal as you will lose all data and have to reconnect to the car again)

Will Tesla Swap my MCU1 for an MCU2 if I have an issue with it?

No, currently they’re still swapping MCU1 with MCU1 builds if it’s a warranty replacement, it’s unclear if this will continue forever.

I have Autopilot 2.0 / HW2 do I have MCU2?

It’s a separate unit so doesn’t come into it. Use the checks above to see which MCU you have.

I’ve paid for FSD will I get MCU2 in the future?

If you bought FSD Tesla will give you the new AP computer (“HW3”) but that’s unrelated to MCU.

Photo of the MCU1 (thanks to https://teslatap.com/articles/autopilot-processors-and-hardware-mcu-hw-demystified/)

Will I get Dash Camera and Sentry Improvements with MCU2?

No, these are part of the AutoPilot system with HW2.5 or above

So how will I get MCU2?

UPDATE SEPTEMBER 2020: MCU1 -> MCU2 upgrades now available for £2000 + VAT.

Nobody will get MCU2 unless a) Tesla decide to offer an upgrade and b) people pay for it.

Do we have an idea on the cost to upgrade?

Not really, it’s estimated that a MCU1 whole replacement would cost you £2,500 so we expect it to be around this price (thanks to Moore’s Law). However, other changes are rumoured to be required as well, e.g. the instrument cluster screen, which means more parts and more labour costs sadly.

If you can upgrade is it worth it?

You will get a faster computer, have improved features but probably the most useful (for everyday use) is the speed up of the navigation and map rendering.

https://www.youtube.com/watch?v=EqqCDi0GeS8

This article uses information adapted from TeslaTap and the knowledge of several in the UK community.

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