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The MCU for my 2018 P3D needs to be replaced. How common is this?

AmokTime

Member
Nov 27, 2019
249
243
Philly metro
Just a quick update, the MCU was successfully replaced by my local Tesla SC. I am happy to report the quality of the service I received was outstanding! They replaced the MCU within 2 business days and gave me a rental car to use while the part was being shipped and the service was being completed. The service rep was in frequent contact with me. I believe Tesla has improved the quality of their service and I wanted to share the good news.

In terms of why my MCU failed and had to be replaced after only 2.5 years, I was curious about the following two possible factors:

1) I never used cabin overheat protection before. My car is parked outside and can often reach internal temps of 140-160 degrees. Could this have contributed to an early death for my MCU? Should I go ahead and use the cabin overheat protection to reduce the risk of any damage to my new MCU?

2) Early on, I applied one of those glass screen protectors to prevent the glass from being scratched. Is it possible that this extra layer of glass could act like a piece of insulation, trap heat inside the MCU, and contribute to an early demise? If so, I will forgo a new screen protector.

I welcome any thoughts so I know how to better protect my new MCU.

Thank you,
joebruin77
The MCU is not in the screen, so no, the glass protector is not a contributor. The MCU is behind the back of the glovebox as it’s been described to me.
 
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Perscitus

Member
Jan 29, 2019
891
571
New York
Hi Joe, for question no 1 - I think the only answer that will carry some weight would be from Tesla themselves... and ideally not just an SC or MS staff person, at least not the ones who worked on your car (to reduce the chances bias skewing the answer). Anything people on here will say is pure speculation.

For no 2 - I doubt Tesla or the sellers of these protectors will have anything worth considering to say. Best to answer that one yourself and do what you think feels right.

Since we haven't heard of too many MCU failures on these cars (early or recent production) and since Tesla will never disclose related stats... we are again left in the realm of speculation.

The screen didnt fail, did it? Just the MCU? As you know its liquid cooled and I bet there are thousands of people who live in desert or tropical climates, have cabin overheat protection permanently off and maybe keep Sentry on 24/7, query their cars alp day via API calls, OE app, etc. Would be great if we knew what offset of these had MCU failures.
 

joebruin77

Active Member
Dec 23, 2018
1,126
985
Encino, CA
The screen didnt fail, did it? Just the MCU? As you know its liquid cooled and I bet there are thousands of people who live in desert or tropical climates, have cabin overheat protection permanently off and maybe keep Sentry on 24/7, query their cars alp day via API calls, OE app, etc. Would be great if we knew what offset of these had MCU failures.

I am still waiting for the final invoice to be emailed to me so I can see exactly what was repaired and replaced. But I believe they did replace the screen because my screen protector is no longer on it. Thank you for your helpful reply.
 
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Shelburne

Member
Mar 9, 2021
176
132
Shelburne Falls, MA
The real question, is what this would cost out of warranty.
I have no idea what it would cost, but I'm sure it will be well up in the thousands. I had a 2002 Jeep Grand Cherokee and after 4 years (just out of warranty of course) I had one of the onboard computers fail. It cost me $1200, and I suspect those MCU's were far simpler than the ones in a Tesla
 

Gasaraki

Active Member
Oct 21, 2019
2,010
1,255
Syracuse, NY
I do not have FSD. At the time of purchase, I did get Enhanced Autopilot, but no FSD. I believe this is the 2.5 version and they are replacing it with another 2.5 version. Glad to hear this is not a common problem. Hopefully it will get replaced soon. Tesla was kind to arrange for my rental car, but man it is hard to go back to driving an ICE car. I have to start keeping track of gas prices again....Ugh!
Are you sure? Why would they put the hardware 2.5 computer in there. It makes no sense. I'm pretty sure you will get the 3.0 computer.
 

Gasaraki

Active Member
Oct 21, 2019
2,010
1,255
Syracuse, NY
Just a quick update, the MCU was successfully replaced by my local Tesla SC. I am happy to report the quality of the service I received was outstanding! They replaced the MCU within 2 business days and gave me a rental car to use while the part was being shipped and the service was being completed. The service rep was in frequent contact with me. I believe Tesla has improved the quality of their service and I wanted to share the good news.

In terms of why my MCU failed and had to be replaced after only 2.5 years, I was curious about the following two possible factors:

1) I never used cabin overheat protection before. My car is parked outside and can often reach internal temps of 140-160 degrees. Could this have contributed to an early death for my MCU? Should I go ahead and use the cabin overheat protection to reduce the risk of any damage to my new MCU?

2) Early on, I applied one of those glass screen protectors to prevent the glass from being scratched. Is it possible that this extra layer of glass could act like a piece of insulation, trap heat inside the MCU, and contribute to an early demise? If so, I will forgo a new screen protector.

I welcome any thoughts so I know how to better protect my new MCU.

Thank you,
joebruin77
I don't think so for the first question and NO for the second.

When your car is sleeping/sitting the MCU is not doing much. 160F heat should be within its operating temps. PC cpus can go up to 100C.
The glass protector will not trap heat. The whole back of the screen unit is metal and gets very hot, most of the heat is coming out from that.
 
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Frank99

April 2018 Model 3 LR RWD, EAP, FSD
Apr 7, 2016
309
408
Arizona
The screen protector isn’t going to make any difference, IMHO-compare the thickness of the several layers of glass already on the display with the thickness of the screen protector.

The electronics are designed to take the heat of the cabin, but high temps might have caused a bad solder joint or weak chip to fail earlier than they might have. When I got my Model 3, COP wasn’t a thing, so the car spent its first summer here in Phoenix without it. I tried to park in shade, but wasn’t always successful and I’ve seen internal temps over 165F (and internal surfaces in the Sun over 190F) with no issues, so I’d say that not using COP isn’t the cause of the failure.

There’s no real reason 99% off the time to turn COP off completely; set it to “No A/C” and it’ll keep the cabin significantly cooler using almost no power.
 

Apone

Member
Oct 7, 2020
85
73
Philadelphia Area
The screen protector isn’t going to make any difference, IMHO-compare the thickness of the several layers of glass already on the display with the thickness of the screen protector.

The electronics are designed to take the heat of the cabin, but high temps might have caused a bad solder joint or weak chip to fail earlier than they might have. When I got my Model 3, COP wasn’t a thing, so the car spent its first summer here in Phoenix without it. I tried to park in shade, but wasn’t always successful and I’ve seen internal temps over 165F (and internal surfaces in the Sun over 190F) with no issues, so I’d say that not using COP isn’t the cause of the failure.

There’s no real reason 99% off the time to turn COP off completely; set it to “No A/C” and it’ll keep the cabin significantly cooler using almost no power.
Did not recall the no/ac option. I leave mine on, thanks for the tip.
 

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