MBA 1466 sensor issue

[Adenitz]

Hello,
I have a problem with my A1466 Early 2015, fan is at full speed and HW Monitor reads multiple sensors on 128°C. One of them is Palmrest sensor. I have excluded the web came by disconnecting the cable and the issue is still there. The trackpad works without any noticeable problems. Actually MBA works without any glitches or slow responses. So, my next step would be to exchange flex trackpad cable, because I have found information that sensor itself is inside the cable and not on PCB board of the trackpad.

Is this appropriate cable for A1466 MBA early 2015?

 

[Audit13]

Have you performed an SMC reset?

Was the MacBook dropped or exposed to liquids?

I don't think replacing the trackpad cable will solve the issue.

If there is a sensor inside the cable, this may not affect temperature readings from other sensors.

I have experience with Airs and Pros that have been exposed to liquids and full-speed fans is one symptom of liquid exposure or drops.

 

[Adenitz]

Yes, it was exposed to a small (but obviously sufficient) amount of water. The problem appeared about two weeks later. I have tried with SMC reset but that didn't help. Tried to disconnect the webcam cable (possible ALS) problem but that didn't help either. nExt would be to try to replace trackpad, but I don't have a spare one. The trackpad works OK and I can use MBA without issues. There is a very loud fan noise that can be controlled by Macs fan control. Usually, when sensor fails and fan goes to full speed, laptop goes in "limp" mode, and it is very inconvinient for work. I can watch youtube videos and Netflix streaming without any glitches.

HW Monitor reads a couple temperatures to be about 128 degC including Palm rest sensor. On apple forums I have found many informations about failed sensors, but in almost all cases it was followed by very slow laptop performance. I have cleaned the flex cable ends and there is no traces of the liquid on the trackpad PCB. It is hard for me to imagine that only sensor failed on the trackpad, but while I can rule out webcam and ALS by disconnecting its cable, this is no option with the trackpad.
The flex cable is so thin, I just can't image there is a sensor in it. I think the sensor is on the pcb of the trackpad.

 

[Audit13]

I have found that liquid exposure causes havoc with the sensors in that the sensors detect the MacBook running at high temperature all the time regardless of its actual temperature.

I can say that changing the flex cable, or any cable, is unlikely to fix the issue.

The best thing to do would be to completely disassemble the Macbook, clean all areas with pure isopropyl alcohol, allow it to dry for a few days, re-assemble, and hope the issue is fixed. If this does not resolve the issue, you may have to have to take it to a repair shop that can perform board-level repairs.

Have you tried running the MacBook without the battery connected?

 

[Adenitz]

Hello Audit,
No, I haven't tried without battery, didn't have reason for that.
Here are the temperatures recorded by HW monitor. On the Internet I found that I can freely neglect the memory bank temperatures, since they're not there on the board.

I'm writing these messages on this MBA, and I can use it normally except there is a loud full speed fan if macs fan control is turned off. So the issue I'm experiencing appears not to affect the performance but it's not that convinient hearing loud fan during system boot. When macOs is loaded and macs fan control application is loaded, the laptop becomes very silent. (macs fan control is adjusted to control CPU temperature).

 

[Audit13]

I suggested disconnecting the battery because it's a simple task that may make a difference.

If one or more of the sensors have failed, it will not matter what the temperature readings indicate because the system will keep the fan running at full speed.

If there is a short on the motherboard, cleaning the board may alleviate the problem.

With liquid spills, problems don't always appear right away. It's the residue in the liquid that remains on the board that causes problems that may or may not be temporary.

 

[Adenitz]

Just a small update, tried with battert disconnected and it's the same. It is interesting to note that fan doesn't go full speed immediatelly after booting up, but when progress bar (white line below apple logo) reaches approx 70%. So the fan speed is ramping up.

 

[Audit13]

You can disassemble the Air, clean all of the parts with pure isopropyl alcohol, reassemble, and hope this resolves the issue. If not, you'll need to have the board repaired.

 

[Adenitz]

You can disassemble the Air, clean all of the parts with pure isopropyl alcohol, reassemble, and hope this resolves the issue. If not, you'll need to have the board repaired.

I did that, but it is the same issue. I got recommendation to try with known good trackpad, but I don't have a spare. I can only buy a new one. I'm trying to see if the problem is on the mainboard or on the trackpad board. The best help for me now, would be to find someone with 100% functional MBA and HWMonitor installed to make a test. To disconnect trackpad and boot to see what sensor failures will HWMonitor report. From what I have found on the internet forums, it is possible that one faulty sensor causing other sensors to report faulty reading as well and that trackpad can be causing this.

 

[Audit13]

You have a link for the HWMonitor app?

 

[Adenitz]

You have a link for the HWMonitor app?

I use this one: https://mac.softpedia.com/get/System-Utilities/HWMonitor.shtml

If you have MBA Early 2015, I would greatly appreciate it to install this and just show me what are normal temperature readings (mainboard 820-00165). It is very probable that some sensors are not built in, so I can have a baseline what is normal.

Thank you.

 

[Audit13]

I attached HWMonitor screenshots from an Air.

 

[Adenitz]

I attached HWMonitor screenshots from an Air.

Thank you. Very helpful. Now, I know, that "meomory proxitimy" doesn't exist. I thought that airport proximity doesn't exist either. I'll investigate the schematics to try to figure out what is mutual for all other 4 sensors. I have closely inspect all parts of the board under magnifier and couldn't find obvious traces of the corrosion.

Thank you Audit, you have been very helpful.

Your post is very helpful since I compare it with the following information:

Mac sensors reference designators - LogiWiki

We have Apple MacBook and iPhone Diode readings and general fault finding information compiled by the leaders in this area

logi.wiki

So all points out that my SMC "3" SMBus is down and from that table:
1. Wirweless (Airport)
2. Mainboard
3. T29 proximity (This could be Memory bank A1)
4. Trackpad

So I have 4 sensors together on U5810 chip. So it is possible that any one of these can pull down the rest. I'll order and try to replace the trackpad.

 

[Audit13]

Thank you. Very helpful. Now, I know, that "meomory proxitimy" doesn't exist. I thought that airport proximity doesn't exist either. I'll investigate the schematics to try to figure out what is mutual for all other 4 sensors. I have closely inspect all parts of the board under magnifier and couldn't find obvious traces of the corrosion.

Thank you Audit, you have been very helpful.

You are most welcome. I hope you are able to resolve the issue.

 

[SmOgER]

It is interesting to note that fan doesn't go full speed immediatelly after booting up, but when progress bar (white line below apple logo) reaches approx 70%. So the fan speed is ramping up.

That's just the way apple does it. Even if CPU suddenly reaches very high temps it will throttle first before the fan reaches max rpm.

The reason yours not running slow is because CPU temp is reading correctly.

 

[Adenitz]

Just want to update. I managed to solve the problem and the cause was not trackpad nor flex cable nor LIO board nor its cable. It was unfortunately waste of time, but the appraoch is to try first what is more probable cause. The actual problem was faulty "Multiple Channel Temperature Sensor" U5810. This chip caused disbalance on SMC 3 bus. It works even without it, even thought three temperatures (memory, mainboard and airport) are out of range. Removing this chip restore Plamrest temperature reading which was the main reason for full speed fan, but also limiting CPU frequency which was not noticeable when working with less intensive applications. Trackpad is on the same SMCBus and in 9/10 cases it is the cause of the problem when reading palmrest sensor out of range. However this was the case 1 out of 10. I have ordered a new chip and will wait some time until arrives. In the meantime, I can use my macbook without any limitations. HWMonitor screenshot is attached. I'd like to thank Audit13 once again for his HWMonitor screenshot , because I didn't have "known good board at my disposal to compare".

I hope this can help someone.

 

[SmOgER]

It's interesting how those readings (sensors) actually differ between the years. Here's how mine mid-2013 looks like:

 

[Adenitz]

Yes, in your case the board is 820-3437 if MBA is from 2013.
Edit:
I can't believe there is no Palmrest temperature reading. Very strange.

 

[SmOgER]

Just randomly saw this. What are the odds?!
It's a glitch as there was no throttling and it recovered itself to normal readings after 5min or so, but yeah still.

EDIT: That specific sensor is indeed buggy in my case jumping between the actual value and 129. Oh well.

 

[aldergood]

Just want to update. I managed to solve the problem and the cause was not trackpad nor flex cable nor LIO board nor its cable. It was unfortunately waste of time, but the appraoch is to try first what is more probable cause. The actual problem was faulty "Multiple Channel Temperature Sensor" U5810. This chip caused disbalance on SMC 3 bus. It works even without it, even thought three temperatures (memory, mainboard and airport) are out of range. Removing this chip restore Plamrest temperature reading which was the main reason for full speed fan, but also limiting CPU frequency which was not noticeable when working with less intensive applications. Trackpad is on the same SMCBus and in 9/10 cases it is the cause of the problem when reading palmrest sensor out of range. However this was the case 1 out of 10. I have ordered a new chip and will wait some time until arrives. In the meantime, I can use my macbook without any limitations. HWMonitor screenshot is attached. I'd like to thank Audit13 once again for his HWMonitor screenshot , because I didn't have "known good board at my disposal to compare".

I hope this can help someone.

I just learn the problem on my MacPro 6.1 is the same to you. The sensor U5810 has been ripped off from the logic board and now fan is running at full blast. May I ask where did you order the chip last time? Thanks