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128C temperature sensor on heatpipe outgoing air.

Hello everyone.

Recently my 2015 MacBook Pro fans have been going crazy as well as the CPU throttling. Going into a temp sensor app indicates that heatpipe 2,3 & heatpipe outgoing air has a temperature of 128C (see photos) which is causing the kernel to think the Mac is overheating and the fans are on 6500 RPM all the time.

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I can’t even use FaceTime at all because it needs to “cool down” when it’s already freezing where I live.

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  • I’ve used a third party app for the fans but the machine is unusable because of it being so laggy. Is there any software workaround it to make the kernel not think its overheating or is there an easy hardware fix which I can do?
  • I’ve tried SMC/Pram reset
  • I’ve tried cleaning the logic board with 99% isopropyl alcohol.
  • I’ve put in a new battery + trackpad and issue still persists even in safe mode and recovery mode

Hardware Diagnostics indicates codes: PPN001, PFM006 & NDC001

Sometimes these codes disappear and Mac runs perfectly but after 20 mins issue comes back CPU overloads once again!

Any expert help will be greatly appreciated!

Edit:

Here are the images after cleaning the LB

All the issues still persist

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I’m suspecting the SMC chip has some corrosion so as the system heats up the sensor input fails so SMC pushes the Fan to the higher RPMs in addition the CPU’s clocking is also lowered as it wants to protect your system from over heating.

At this point you’ll need to remove the logic board and inspect it throughly on both sides. Follow this guide MacBook Pro 15" Retina Display Mid 2015 Logic Board Replacement and take note of any corrosion, discoloration, staining or visible damage on any of the parts. If you can take some good pictures and post them here for us to review Adding images to an existing question

Update (02/08/2022)

Generally the board looks clean I don’t see any obvious issues which is a good thing!

You’ll need to get a bit deeper here as the images are not at the needed magnification to see much. I’ve marked up your images which you need to look deeper.

Often times I find going over the solder joints can catch a cold solder joint. Do you have access to a hot air workstation? If you do place some flux on the joints and reheat them. If you don’t you’ll need to find someone with the proper tools to rework the logic board. Don’t try to do this with an iron as all you’ll do is make a mess.

Here’s the areas

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and the SMC its self if the upper two doesn’t fix things.

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Guide

Adding images to an existing question

Difficulty:

Very easy

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2 - 5 minutes
MacBook Pro 15" Retina Display Mid 2015 Logic Board Image

Guide

MacBook Pro 15" Retina Display Mid 2015 Logic Board Replacement

Difficulty:

Difficult

—

1 - 3 hours

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I’ve included images @danj

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Good day Lakazai

Was there ever any resolution to this? I have a similar issue with a customer's 2017 MacBook Pro 13" (With Touch Bar). Ive double checked every connector on the mainboard. Gone through both sides of the board closely inspecting for corrosion or physical damage. Nothing stood out. But HWSensors showed 3 temperature sensors ramped up to 128c (2 heatpipe sensors and Airdrop Proximity sensor) Nothing was hot on the board at all. Fans are spinning at maximum RPMs and the proccessor is operating at a fraction of its capacity. (Similar to an automobile's "limp mode")

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@ludvanb - Give this a try install this great app TG Pro the full version offers a good diagnostic which should help in isolating things a bit better. Once you got it going take a snapshot of the main window posting it here for us to see as well. Often times one needs to dig into the logic board using the systems schematics and board view drawings for reference.

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