MacBook Pro 2019 fan running at full speed after macOS Sequoia 15.7.3

When you performed a clean install of macOS, did you test the laptop before installing any third party apps, or restoring from a backup? Or before signing into your AppleID/iCloud? If not, then you likely just brought the problem back. Make sure to disconnect all external devices too.

If the clean install without any AppleID/iCloud, without any third party apps, and without any restore from backup still had the problem, then the laptop has a hardware issue.

If the issue is only occurring with your apps installed, then run the third party app EtreCheck and post the complete report here so we can examine it for possible clues.

How to Post an EtreCheck Report

FYI, the Apple Diagnostics (even the service diagnostics) are a joke these days. They only check that various hardware components are communicating and only perform the a quick very basic memory test. About the only thing it may do somewhat well is checking the cooling system (fans & temp sensors). Otherwise the only useful diagnostic result is one which reports a problem. A passing result is meaningless.

I don't recommend repairing any Intel Macs (especially the USB-C models) for multiple reasons. The money spent on repairs is better spent on a new laptop.

Kanjanappilli wrote:

Hello everyone,

I am using a MacBook Pro 2019 (Intel i9, T2 chip), and I started facing a serious issue immediately after installing macOS Sequoia 15.7.3.

From the moment the Mac powers on, the cooling fans run at full speed continuously, even when the system is completely idle and cool. This behavior was not present before this macOS update.

The Mac shows no heavy CPU usage, and the fans and vents are clean.

Troubleshooting steps I have already performed:

• Cleaned internal fans and vents

• Reset SMC and NVRAM

• Reinstalled macOS multiple times

• Performed Internet Recovery

• Performed a DFU restore using another Mac

• Verified the issue still persists after a clean installation

You are on the right track so far.

About diagnostics:

• When trying Apple Diagnostics with the D key, it initially showed “Waiting for support…”.

• Apple Support then performed hardware diagnostics remotely, and the result showed “No issues found”.

Because of this, I suspect the issue may be related to thermal sensor handling, SMC behavior, or firmware interaction introduced with macOS Sequoia 15.7.3 on Intel T2-based Macs rather than an actual hardware failure.

From here, I would try to run and complete the Apple Diagnostics Test myself.

Use Apple Diagnostics to test your Mac - Apple Support

Take the MacBook Pro to my local AASP.

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