Model S

MCU Failures

edited November -1 in Model S
Is anyone tracking MCU failures like they are tracking Updates? It would be really interesting to know how many MCUs have failed. What age they failed at, years and miles? What was the cause of the failure, i.e. was it the logging memory chip?

I suspect Tesla knows but probably would not tell us.

Also I wonder how many FSD cars were purchased along with how many are MCU 1, AP 2.0, 2.5 and 3.
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Comments

  • edited November -1
    There have been a few dozen reports in the forums, but no way to know the actual number. Let's say there are 10 times that amount that has failed - 250 units.

    About 330,000 model S and X were made with MCU1.

    So the failure rate is 250/330,000 = 0.075%, a fairly small number over 8 years, although some MCUs are newer than others.

    We have no data on the nature of the failure, as that's internal to Tesla. The memory chip that seems to fail on some MCUs is used for storing the software code, settings, logs, and other information. I did an analysis in another thread that shows the logging is unlikely to cause the failure of the chip, despite many unknowingly saying logging was the cause. With all the new features added over the years, and especially AP, it may push the chip to its limits and cause some early failures. Failure causes are mostly conjecture so be cautious about coming to any specific conclusion.
  • edited February 6
    Put me on that MCU failure list. Model S 85d built Nov 2015. 68k miles. Just out of warranty I’m told. Repair cost to be $3k
  • edited November -1
    10 people could have a failure, but 110 people talk about it and the problem magically becomes bigger than 10.......

    I understand what the OP’s intentions are, but this is yet another thread about this which just leads into my example above.
  • edited February 6
    Um, no actually, the engineering problem has been figured out in detail, and there are people who have entire businesses replacing the chip - so way more than 250. It is apparently a design issue that will affect all Teslas once they hit the magic read/write number. And the number of reported failures is way more than a few dozen. My ranger (now friend) says this will affect all pre-Raven/3) Teslas, no exceptions, it is a ticking time bomb - as BH has reported, not generally fatal to travel, but inconvenient as hell. It can't be a forced safety recall because the cars remain generally driveable, albeit with crippled functionality. Tesla needs to start owning this. My sense is that if they make it a priority, the cost should not be too much.
  • edited February 6
    Mine made it 283k miles with tons of MCU input
  • edited November -1
    MAJOR issue tonight. Wife was driving the 2013 S with 175k miles. Screen resets are slow to reboot usually but they always work. Today, it froze while driving, did the usual scroll wheels reboot, and nothing. AC stayed on, no access to anything. Got home, parked, went out a couple hours later, 20 miles gone, and AC/FAN is still blowing. Tried the resets, numerous times, and even pulled the #51 fuse. The fuse pull stopped the fan... but screen still won't come on. So did I get a full MCU failure? Any ideas? Thanks all. Will repost this in main board for more answers.
  • edited February 6
    PD, wasn’t dismissing anything. I am merely pointing out that affect of a lot of people talking about a single problem. BTW what is the magic limit? What is considered a “read/write”?
  • edited November -1
    BH said his lasted 283,000 miles. For the average driver that’s 18.8 years of driving. I assume these “read/writes” happen when the car is in use and OTA updates.
  • edited February 7
    Not sure I'd call it a ticking time bomb. Yes, it will fail someday. So will the battery, tires, motors and just about everything else in the car or any other car. On any given part failure, some people may get 50K miles and some 300K miles or more. I'm not aware of Tesla offering a lifetime warranty on the car.

    As for the number of failures, let's take a WAG it's 10 times my first estimate or 2,500 units. That's a 0.75% failure rate. Still fairly low over 8 years of production. Still, it sucks when any expensive part fails, but I don't see Tesla providing replacements for free out of warranty.
  • edited February 7
    Any ICE has a head gasket or two ( V6, V8, V10, V12) that may very well let go and that is not exactly a $200 job......

    I know someone who had a boss that owned an Audi L8. It was $1,500 just to replace the thermostat due to everything that needed to be removed and re-assembled.
  • edited February 7
    Just paid $2933 for my obligatory MCU replacement today. 2015 85D. Just out of warranty (of course). I suspect my story is (or will be) as common as it is frustrating. I do feel this issue should be on the level of recall since it is actually caused by overactive use by Tesla (e.g. logging) for their own purposes.
  • edited February 7
    Does anyone know if Tesla will install a privately purchased MCU? And if you did get one installed from a private mechanic, does it completely screw up the car? In other words, if I bought one on Ebay, would it come up in my car as the car it came from? Or will Tesla program it?
  • edited February 7
    MCU got replaced under warranty due to a screen issue (a line of pixels went out). Current MCU has about 150k miles/6 years and needs out-of-warranty replacement.
  • edited November -1
    I believe there is a setting where you can decline sharing driving data with Tesla; perhaps that will reduce the read/writes
  • edited February 7
    2015 85D Mine failed in June of 2019, at around 72,000 miles. $2400
    It was the memory that went bad/corrupted. So sad that a $70k+ car needs this kind of work after 4 years. I really don't care about comparing ice cars; I didn't purchase one, so why should I feel better about comparing repair costs? Maybe we start comparing repair costs to the few other EV vehicles.
  • edited November -1
    steveb,
    Did they give you an MCU1 or an MCU2?
  • edited February 7
    $100 says they gave him MCU1
  • edited February 7
    Bill - your bet isn't big enough :-)
  • edited February 7
    Yes, MCU1. At the time (June 2019), SC said I could not upgrade to MCU2. "Tesla" wasn't doing them.
  • edited November -1
    2 friends replaced their MCU1 recently for $2200 each. One of them had 130k miles and the other 225k miles.

    brdinjd

    You must have had something else done, because MCU1 prices don't vary from state to state. I just contacted my mobile tech and was told it's the same price across the country unless something else needed to be done to the car.
  • edited November -1
    steveb | February 7, 2020
    2015 85D Mine failed in June of 2019, at around 72,000 miles. $2400
    It was the memory that went bad/corrupted. So sad that a $70k+ car needs this kind of work after 4 years. I really don't care about comparing ice cars; I didn't purchase one, so why should I feel better about comparing repair costs? Maybe we start comparing repair costs to the few other EV vehicles.

    I don't have issues comparing to other EV vehicles. the Nissan leaf a friend (also owns an 85d) owns had to replace his suspension system for 2500 @ 55k miles and he's also down on his range by 40%. He the got quoted over $2k to replace his charge port a few miles later.
  • edited February 7
    PS: I have 239k miles on my car and spent only $2,600 out of pocket to repair my car out of warranty.

    repairs include:

    steering u-joint (combined with rear toe links) $962
    rear toe links
    1 front air shock $883
    parking brakes (I did that myself) $500 for parts
    1 tie rods - $216
    wiper pump $38

    I've saved tons driving my car and would not bitch at all if the screen failed like my friend did daily!
  • edited February 7
    2 tie rods
  • edited February 8
    Mine failed at 3 years and 35000 miles, the centre console just cycled. I was unable to enter a PIN to drive so it was a case of the car being taken away on a low loader
  • edited February 8
    Failed and was pure torture to diagnose and replace. Told my wife would be ok to drive with no center screen and supercharging would still work. She ended up stuck and waiting for a tow turning an already expensive repair approx $2200 into pure hell. I believe Tesla knows all computers will fail with time and need replaced. Feels like it should have been covered by Tesla as the problem of too much data was created by Tesla. Was quoted 4000 to fix a headlight issue, then with discussion price came down to 2000, then 900, replaced off ebay for 135 in parts and $100 in labor at local shop and also got tires rotated for free instead of $500 I was quoted to rotate tires by Tesla.
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