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The larger of Apple's MacBook Air laptops featuring dual microphones and 802.11ac Wi-Fi connectivity.

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Could these missing temperature sensors be causing the problem?

So after scouring lots of other questions and answers, I haven't been able to solve the case of the snails pace processor in my girlfriend's Macbook Air dual-core i7 (mid-2013). Here is what I know or have tried so far, based on questions from people reporting similar issues.

  • When i ran apple diagnostics, it reported error code PFM006 problem with the SMC.
    • I just noticed too that in my system profile, it lists the last diagnostic run as giving reference codes PFM006 and PPN001. I didn't see it say anything about PPN001 when I actually ran the diagnostics, but according to the system profiler, it was both PFM006,PPN001.
  • I tried twice to reset the SMC, no change in the problem. Computer still operates at a snails pace, with activity monitor showing that kernel_task is taking up 300% of the cpu. Oh, also i think the fan is running at constant high speed -- but i'm not 100% certain as its my girlfriends computer.
  • Booting it into safe mode doesn't fix the issue either, so it doesn't seem to be a third party issue. It still exhibits the same problems as mentioned before.
  • I reinstalled Mac OSX (it has Big Sur 11.7.7 running on it). This didn't seem to help anything either.
  • I also ran the all disk utility repair options on all the volumes (first aid? repair? i forget the names of the two "evaluate and fix" type options inside disk utility). Every volume I was able to run both commands through to completion, nothing indicated there were any issues or fixes for any issues. I did this while booted into recovery mode. No improvement.
  • There hasn't been any liquid spills or anything out of the ordinary that happened to the computer preceding this.

So one of the more promising leads I have found, which I think might be the issue, is that when I downloaded iStats menu and pulled up the temperature sensor dropdown, it has just a "-" listed instead of temperatures for the following sensors: CPU Proximity, Camera Proximity, Charger Proximity, Inlet. Some other people who had similar problems said it ended up being a faulty temperature sensor that was the culprit, which they identified by there being "-" instead of a temp for that sensor, except for them it was the trackpad's temperature sensor. The trackpad sensor seems to be okay here though, reading 75 degrees. Those four other sensors though each read "-" -- could this be the issue?

I am including a screenshot (well, a picture taken of the screen from my iphone) of that istat menu with all the sensors and readouts in case that contains useful information I am simply not able to interpret out of it.

Block Image

Thank you, in advance, for any insight you can lend!

UPDATE: So after doing some more searching, I think its not necesarily an issue with the four sensors, but rather the BUS they are all connected to. On this page: https://logi.wiki/index.php/Mac_sensors_... I found that those 4 and only those 4 sensors are all located on SMC S0 "1" SMBus -- which probably isn't a coincedence, i'm guessing the problem is probably at least up on that specific level.

So my updated question is this: is this something that I could even attempt to fix myself? I am halfway decent with a soldering gun, but like.. i know if the problem exists within the LCD display there it's simply not gonna happen. I would be willing to try replace a component on the board though. Any thoughts on this would be super appreciated.

Ответ на этот вопрос У меня та же проблема

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@flannelist I bet you get this resolved quickly.


is the fan spinning, theres 4 different things there showing no temp and i think normal cpu temps should be around 40s when not really over used. the other dan might know more about this but 4 inactive temps seems strange


Yes the fan is spinning seemingly at maximum speed at all times. The temperatures are in Fahrenheit if that makes a difference. I was wondering if the inactive temps might mean the sensors need to be replaced. I am not a master at soldering but I would be willing to try, even if is difficult. The laptop is so old that its almost certainly not going to be worth taking the apple store.

Alternatively, i wonder if its possible that this particular macbook air model doesn't have some of those sensors to begin with?


@oldturkey03 @subtlehyperbole Please feel free to bug me if I haven’t weighed in on this later. I do not want too forget. But my brain is ver distractable right now. I’m en route to work and I’m late, (via bus don’t worry, I don’t fix and drive). So I don’t trust myself to come back to this. But this is not an I can just wing off a quick answer question. I would at least want to look at the schematic first. And come prepared :)

(The details in this question are fabulous by the way)


@subtlehyperbole just as a confirmation, and I think we all agree for now Slow processing==>fan at full speed==>bad sensor.

Looking at the screenshot I would have to guess, which would not be fair to you. We‘ll let @flannelist and @tech_ni guide and teach us on that.


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This is definitely a sensor problem. The issue going top be tracking down the specifics. But I think you’re on the money here honestly. All of your reasoning is solid. This sounds like it’s either an issue with the “sensor chip” or one of its outputs.

This is a QFN chip with a center ground pad. It’s not a chip that requires a huge amount of skill to replace, and it’s probably worth a go. I would hate it. I will take a BGA over one of these QFN chips with a giant ground any day, especially on a Mac. I always feel like I’m going to roast everything trying to get it off because the ground ppl and on the board just sucks up all the heat you throw at it. Bottom heat helps with these. But a board preheater isn’t something everyone has.

That being said. I would still want to get eyes on that area of the board. It’s designator on the schematic us U5800, and it’s about smack dab in the middle of the back of the board (back being the side that’s facing the keyboard when it’s installed). I’ll try and remember to throw a pic in here when I’m on lunch.

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