Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

NHTSA Investigates Failing MCUs

This site may earn commission on affiliate links.
Interesting. But if you provide the safety system - and it fails by the thousands...There is clearly a safety issue that could result in a recall (regardless of a mandated). That's my opinion.
NHTSA is far more concerned with emergent safety issues vs. general component failure.

Illustrative examples:

Headlight bulbs that burn out / fail at a higher than expected rate are generally not recall-worthy.

Car electrical systems that could cause the headlights to unexpectedly completely fail WHILE DRIVING are a recall-worthy safety issue.

The inability to control the HVAC/defroster isn’t generally a recall-worthy safety issue. Even if such controls fail while driving, you have more than enough time to pull over safely.

Same with windshield wiper motors that fail. There’s a difference between component failure and unexpected or intermittent failure of the complete system that could cause a crash.

A backup camera failure isn’t generally an emergent safety issue generally worthy of a recall. You’ll always know the backup cam isn’t working before you even start to back up, and can choose not to if you can’t do so safely.

IMO the best possibility for this to be considered a recall-worthy safety issue is the turn signals not working. Everything else is pretty minor and doesn’t create an emergent, unexpected safety issue while driving.
 
A backup camera failure isn’t generally an emergent safety issue generally worthy of a recall. You’ll always know the backup cam isn’t working before you even start to back up, and can choose not to if you can’t do so safely.

While I agree with most of what you said, the NHTSA seems to take the backup camera seriously, at least for cars manufactured after it was required. They went as far as to demand a recall from one manufacturer because the backup camera wasn't restored to default brightness/contrast settings each time it was turned on like the regulations require. But again, no Tesla with MCU1 is subject to the backup camera regulations, so that probably isn't relevant.
 
  • Informative
Reactions: ucmndd
It would be interesting to know what the failing MCU does to the passenger airbag lock or to the kid door safety.
If the car is drivable but one of those two features get disabled without any warning, this would be a safety issue.
As a parent of young kids I have always been concerned by these two legally mandatory kid safety features being toggled by a software button. In any other car this is a hardware switch toggled by the car key, in the glovebox and near the door lock.
 
NHTSA is far more concerned with emergent safety issues vs. general component failure.

Illustrative examples:

Headlight bulbs that burn out / fail at a higher than expected rate are generally not recall-worthy.

Car electrical systems that could cause the headlights to unexpectedly completely fail WHILE DRIVING are a recall-worthy safety issue.

The inability to control the HVAC/defroster isn’t generally a recall-worthy safety issue. Even if such controls fail while driving, you have more than enough time to pull over safely.

Same with windshield wiper motors that fail. There’s a difference between component failure and unexpected or intermittent failure of the complete system that could cause a crash.

A backup camera failure isn’t generally an emergent safety issue generally worthy of a recall. You’ll always know the backup cam isn’t working before you even start to back up, and can choose not to if you can’t do so safely.

IMO the best possibility for this to be considered a recall-worthy safety issue is the turn signals not working. Everything else is pretty minor and doesn’t create an emergent, unexpected safety issue while driving.
Not true. My backup camera/MCU went from working to black/off while I was looking at it and backing into a parking spot. Stayed that way for several minutes then it came back on. It was quite a shock. The next day, MCU turned off/restarted again going 70mph. Since then, it has not happened again. Tesla unable to find any issues with date/time stamp, and video of it occurring both times. So, I NEVER know when the backup camera is going to fail.
 
Last edited:
I’ve just joined the failed MCU1 club (2015 85d). Started a couple of days ago, WiFi log shows car not connecting to the home WiFi. I noticed it when my phone didn’t pair. Tried two button reset, no luck.

The climate control is now on, and I’m unable to turn it off. Service has been contacted. So disappointed with this, the car is only 5 years old.
 
  • Like
Reactions: InternetDude
FWIW, when my MCU failed (black screen), brake lights and the turn signals still worked but makes no noise, charging still worked, Windows still work, the small display still shows velocity, windows still worked. No a/c, no heater and all the convenience feature gone. Eventually it switched from metric to imperial (miles/h).

Highly annoying, and must be fixed, but is it a safety issue? Perhaps in extreme weather.

The nature of the failure is that flash memory cells get rewritten too many times and they fail. When too many cells fail, the flash memory become unusable (can’t be read). The writes are what degrades the cells, not the reads.

The real fix is to always have a large number of free available space ( > 50%) - or double the size of the current Emmc used but limit the file system to never exceed 45%. All flash memory file systems today will do load balancing, meaning the request for a new allocation unit to write into will rotate to avoid wearing down the same cells. This way, the flash memory will last a decade or even longer. One of the After market fixes uses the emmc that is twice as big and should last decades.
 
Last edited:
@Chaserr

Yup same comment. Instead of just blindly disagreeing and being a sheep please add some input about how and when hand signals are to be used in the event of a signal failure.....
Note : in my case, the turn signals went silent, but they still worked, you just can’t hear the fake clicking sound generated when the signal lights are flashing. If other see that the signals don’t work, then that’s different from what I saw.
 
Hand signals will trump the signal or lights not working......so no ticket will be issued as long as the hand signal is visible to the officer and done correctly
I can't say about the legality, but as someone without working turn signals and hauling a camper, I can tell you it's nerve-wracking and clearly a safety issue. Hazards do still work, so I took to flashing my hazards to draw attention to my (far away) hand signals on a recent trip.

As I mentioned upthread, the NHTSA has a whole page of studies that they've funded dedicated to showing the safety implications of working signals, so they're very likely to consider it a safety malfunction. As they should.
 
So what does Tesla even say to NHTSA after being presented this evidence.

" Um turn signals work i guess for the most part. Driver doesn't need AC or defrost. Um we fixed this via software update. Don't really need back up camera, our car parks itself"
 
So what does Tesla even say to NHTSA after being presented this evidence.

" Um turn signals work i guess for the most part. Driver doesn't need AC or defrost. Um we fixed this via software update. Don't really need back up camera, our car parks itself"
I don't think it's valuable to put words in others' mouths. Same with projecting what "Tesla fanboys" might say. Let's address Tesla's response when they have one. Focusing on what is really happening, instead of some caricature of what might happen, is a much more valuable exercise in my opinion.
 
So what does Tesla even say to NHTSA after being presented this evidence.

" Um turn signals work i guess for the most part. Driver doesn't need AC or defrost. Um we fixed this via software update. Don't really need back up camera, our car parks itself"

At this point NHTSA isn't really presenting evidence. But they have asked Tesla 15 questions, but they are all big questions. Like this one:

13. Provide the following information regarding subject eMMC memory devices:
a. Supplier;
b. Data sheets;
c. Storage capacity;
d. Describe the layout/configuration of the eMMC flash memory;
e. Describe error correction and wear leveling strategies that may affect device durability;
f. Rated number of P/E cycles;
g. Nominal daily P/E cycles;
h. Describe all OTA updates affecting P/E cycle use rate that have been released by Tesla;
i. Factors that influence daily storage use (with estimated upper bound); and
j. Expected service life in

Their response is due on 8/7/2020, unless they ask for and get an extension.
 
@Chaserr

Yup same comment. Instead of just blindly disagreeing and being a sheep please add some input about how and when hand signals are to be used in the event of a signal failure.....

Hand signals are valid but are meant to be used in extreme emergency situations. Case in point, when I was in college (late 90's) I was driving home one day in my car and the alternator failed (unbeknownst to me) causing the car to use and discharge the 12V for all electronics. At some point during the 30 minute drive, the radio became crackly and started fading out. I then went to make a turn and realized the directionals and other electronics were no longer working.

Knowing I had a battery/alternator issue at that point and no turning/brake lights, I used hand signals the rest of the way home and managed to make it to my driveway right before the 12V lost the ability to provide spark and the engine died.

This was a valid use for when hand signals are to be used. Hand signals are not meant to be an intentional day-to-day replacement for turn and stop signals.
 
Well - guessing what Tesla may say or do is still a valuable exercise. This is the internet of course....

I certainly like the 8/7 deadline.

I have a 2015 with 84k miles. I stopped streaming, shut satellite off and don't really use Nav. I have also rejected the current software update. All this because I had a 45 sec wait when turning car on. So I am acting paranoid. And I am doing pretty well on my current update.

Turns out the 45 sec wait was after not being driven for a long time and I guess people see that sometimes. But I don't want to get forced into a $1300 partial fix - ie same defect in refurb unit when NHTSA might force a free repair with a better eMMC chip. And yes, I might get reimbursed but I might not.

So I need some guessing/conjecture or whatever.
 
I’ve just joined the failed MCU1 club (2015 85d). Started a couple of days ago, WiFi log shows car not connecting to the home WiFi. I noticed it when my phone didn’t pair. Tried two button reset, no luck.

The climate control is now on, and I’m unable to turn it off. Service has been contacted. So disappointed with this, the car is only 5 years old.

An update. Climate control is still on. I’ve tried to reach Tesla Service several times, but no reply. This will suck if the CC fan fails. Feeling very disappointed, this car has otherwise been a pleasure to own.

Anyone have a link to the NHTSA complaint site?
 
March 2015 S85D, and I’m right there with you.

2015 85D as well with ~55k miles and pretty sure my eMMC failed yesterday. Had to get the car towed to Tesla (took about five hours to get through to someone). Just got a text that they won’t be able to diagnosis it for 4+ days. They gave me a bunch of Uber credits but there’s almost never an Uber available. Pretty frustrating.