Fan running noisy, but Istat Pro says it's 0rpm.


I've spilled water on my MBP. I've dried it out but my fan started running noisy even though IstatPro says it's 0rpm. Whenever I turn the MBP on the fan starts automaticly and will stop only when I turn it of.

I did PRAM and SMC reset but it did nothing. I've runned AHT and it said it was a fan issue, which made me buy a new one and which did not solved the problem.

I've looked for similar issues but haven't found any answer that wouldn't take me to a Logic Board replacement (which I wan't to avoid, 'cause I'm not apple cared or anything...)

Thanks a lot

ps: sorry about my english, I'm brazilian and not the best english speaker.

Edited by: caetano ( )

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If you hear a fan running on high- it's most likely because a sensor is damaged. The default condition when a heat sensor malfunctions is to run the fan at maximum in order to prevent further damage to heat sensitive components like the CPU. Examining the board under a magnifying glass might find or point out corrosion or burned components. You may need to examine both sides of the board.

So the problem is probably not the fan, but a sensor. Sometimes you have to run AHT 2 or 3 times in a row to get useful results... especially if it's an intermittent, or, overheating problem (if the unit isn't hot then the problem won't occur). If it tosses out an error the complete text of the error usually indicates which sensor has failed. So maybe you only need to replace a sensor.

At this point, with the machine not working, you have little to lose and much to gain... you just have to decide how to spend your money. In decreasing order of cost:

A liquid spill is not a covered claim under Apple care - try asking for a depot repair (that's the best price Apple repair).

You might try a local shop that is Apple Certified and see what they wold charge.

If you have good reading comprehension skills you could try to do the logic board replacement

yourself. Study the guide - before you begin, especially directions/cautions about disconnecting cables etc. Most problems and damage come from someone tearing a connector off the board because they didn't unlock it, or, pulled in the wrong direction or way.

If this Answer is helpful please remember to return and mark it Accepted.

Hi machead3, thanks for your time and for your answer! I've runned AHT more then 5 times in a row and it keeps giving me the "4MOT/4/40000002: Exhaust-0" error. I'll examine the board then, but I have to say that the machine is running ok (at least it looks like). The CPU temp is about 40ºC (with peaks of 60ºC)... Do you think it could be the heat sink? Thanks again for your time!


To me, since you hear a fan running, and there is only one fan, it's a sensor error that is incorrectly "reporting" to the EFI that fan is dead. I don't know which sensor, or if it they are soldered to the board, or, if they are attached. So go over the board very carefully looking as small block connectors for scorch marks, corrosion or being lose or having damaged wire. If you find something address correcting it. The "DIY" fix - though its a tough one since it involves completely disassembling and reassembling the machine, would be a logic board replacement. Of course you could continue to use it (keeping a current backup - time machine is good for this) until the it stops working altogether, at which time you'll have to replace the board, (if you get the proper tools, & study the guide carefully) you could try DIY since, at that point, you'll have nothing to lose. Or, you could part out the rest of laptop.


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