Model A1419 / Late 2012 / 2.9 & 3.2 GHz Core i5 or 3.4 GHz Core i7 Processor

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Apple error 4MOT/4/40000003 Main-3827

After upgrading to SDD the fan runs at a constant 3800 rpm. I installed OWC Digital Thermal and when that didn't work I installed Mac Fan Control. The readings for hardware on MFC are normal with nothing peeking over 100°F/37°C.

No matter what profile I apply in MFC the fans still spin at 3800rmp. Ran Apple Hardware Test which returned the following error:

4MOT/4/40000003 Main-3827

Update (10/13/2016)

Maybe it's the battery?

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Update (10/13/2016)

Dan, I noticed the "Main 3827" in the error code is the fan speed. "Main" is the only option in Fan tab of Preference window.

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Update (09/28/2016)

Maybe it's the internal battery?

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Answered! View the answer I have this problem too

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No its not the batt sensor, unless you've got a new type of laptop ;-}

mmm... I was hoping one of the sensors were damaged. Well we need to go back to the fan as the RPM feedback is the issue as I stated the AHT error was the fan unit. But as you've replaced it with a new unit we need to focus on the logic board circuitry. Somehow it got damaged.

Sadly, you'll need to find someone with deeper skills & tools here to diagnose the logic board or you'll need to replace it.


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Chosen Solution

The AHT error is a fan error. Unlike the older systems this one only has one (main).

Did you disconnect the fan in the process of disconnecting the speaker and not plug it back in correctly?

The other possibility is the OWC inline thermal sensor is defective. You might want to call OWC to see if they have an idea here.

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Here's an update to what I've done. I took the OWC thermal sensor out of the equation and ran only Macs Fan Control. Issue was still resent. I've installed smcFanControl and HDD Fan control (uninstalled each software before running another) and neither can stop the fan from spinning at 3800 rpm.

I ordered a new fan and to my to disappointment it still running at 3800rpm. I've reset the SMC and NVRAM. I'm at loss as to why the machine once the power button is turned on runs at a constant speed it till it goes to sleep or is turned off.

I can however take the iMac completely apart with my eyes closed.


Did you contact OWC?

Lets try this, download this app: TG Pro for less than $20 US is worth it. Lets see if we can get some idea on what the thermal sensors are doing.


Dan, First and foremost THANKS for taking the time to help with this issue!

I did contact OWC and they were not able to provide a solution. I removed the OWC senor to see if it was faulty and the fan with fan control software still spin at 3800 rpm. Once I mentioned this to OWC the tech determined it was not the sensor since the issue was still present when using software. It was enough reason for support to not give further assistance.

I downloaded the trail version of TG Pro. It's inexpensive and if it solves my issue then well worth the investment. So far none of the fan control software I've tested have been able to stop the fan from spin at 3800 rpm (3828 to be exact). The software in trail is no different. The fans go off a soon as I hit press the power button. I'm not sure if purchasing TG Pro will do the trick if I can't get the fans to slow down in trial. Sensor, software nor new fan can stop it.

Based on TG Pro the average temp is 117F. Nothing close to red lining on any of the components.


I was recommending it to help isolate the sensor that is not working, not to control the fan. Take a screen shot of the main screen which shows the temps and the Fan's RPM and paste it here so I can see it.


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jose segura will be eternally grateful.
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