Heat Sensor Problem 4SNS...Th0H

For some time my MacBook Pro has been running slow and the fan runs constantly. The closest Apple store is 3 hours away and I haven't had the ability to surrender my laptop for more than a day so I've just been living with it.

I ran the Apple Hardware Test today and it gave me the following code:

4SNS/1/40000000: Th0H - 78.250

As best I can figure, this points to a heat sensor but I can't tell if its something I could fix on my own or if I'm at the mercy of the unavailable and expensive Apple Store. The only repair guys within a reasonable distance have a horrible reputation so I've done everything myself up til now. I think this may be above me, however. Is it?

Help? Anyone? TIA!

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try to download "iStat" and see what it tells you on the heatsink side.


Thank you, oldturkey03. I downloaded iState (very cool, thank you!) and captured two readings several minutes apart, after resetting PRAM and SMC. As follows:

HD 42/42

CPU 94/70

Airport Card 51/48

Enclosure Base 26/26

GPU Diode 91/84

GPU Heatsink 71/66

Heatsink A 69/65

Heatsink B 47/46

Right Fan 4292/4360

Left Fan 4292/4364

I have no idea what these numbers mean, though! Any help interpreting them would be super appreciated! TIA!


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1 Answer

Chosen Solution

Overheating, and the high speed fan will slow the machine down. I couldn't find the location of thOH. Sensors are spread throughout the machine, not just on the logic board. As a work around using a cooling pad would help, but it's not a fix.

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machead3, that's a zero, not O - Th0H, zero H. Does that help at all? Thanks for the tip!


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