I am using istats to see the speed of my fans:

enter image description here

I ran a diagnostic by holding down d during a restart and it came up without any errors. I've also reset pram and the readings are still really high. Is there a hardware error? What do I do to get correct readings again? I am on a 2018 15 inch i7 macbook pro and I'm quite concerned because all I have are a few chrome windows, spotify, and a terminal open. Having a CPU temperature of 43 degrees seems absurd.

EDIT: The widget Fanny also displays these speeds https://www.fannywidget.com/

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    43°C is nothing. In fact, some would argue that even at idle it's a low reading! MacBook Pros regularly run in the low 100°C range when under a heavy load, and probably average around the 50°C to 70°C range in normal usage. Also, ambient temperature will have an impact on temperature readings too. – Monomeeth Jul 26 '18 at 4:02
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    One question...are you getting the fan speeds from the utility alone or actually hearing your fans spin at a high rate of speed? – Allan Jul 26 '18 at 13:11
  • My fans are making quite a bit of noise but there's no reason for the speeds shown in istats. – Curtis Chong Jul 27 '18 at 1:33
  • This is interesting reading about CPU temperatures: blog.codinghorror.com/an-inferno-on-the-head-of-a-pin – Thorbjørn Ravn Andersen Jul 27 '18 at 14:28

There’s a lot to answer but here are my thinking:

  1. Power off your Mac and reset the SMC one time - those blower speeds are non-sensical and look like an integer overflow.
  2. Run software updates - apply EVERYTHING and consider downloading the OS installer and running it from Recovery HD - install right over your system as that won’t erase any accounts or settings and it will download EFI / firmware updates as needed - especially if you’re connected to a viable network when you reinstall.
  3. A temperature of 100 C isn’t ridiculous - modern CPU run at the boiling point perfectly fine for extended periods - 43 C is a cool fall evening with a fresh breeze and nothing to worry about at all.
  4. Don’t put much stock (if any) in the diagnostics - that’s designed to detect major component failures - not any sort of battery or fine grained test in my experience. Even the tests Apple runs at the Genius Bar while you wait are pretty trivial, basic tests.
  5. Only 3 cycles on a battery makes me think you have a new Mac - be sure you contact iStat menus to be 100 % sure the software fully supports your specific model. I have seen new machines report nonsense until the vendor updates their software for new hardware and new sensors.
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    Agreed - the fan stats are nonsensical! I reckon your speculation that the software hasn't been updated yet to support the new MBPs is spot on! – Monomeeth Jul 26 '18 at 4:00
  • restarting the SMC didn't work. I guess I'll wait for a software update as jmh's program could keep track of the fan speeds. – Curtis Chong Jul 27 '18 at 1:30

You should load the app Macs Fan Control from here. This app will tell you the temperature of key parts of your mac and also allow you to control your fan speed.

enter image description here

  • Surprisingly Macs Fan Control worked Thanks! However iterm still reads my speeds as a really high number :( – Curtis Chong Jul 27 '18 at 1:31

The only thing that worked for me was resetting SMC (System Management Controller).

Press SHIFT OPT CTRL and the Power Button at the same time.

For more detail read here.

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