iOS4 update - now iPhone now reboots during phone call

I just had mine replaced in Australia. IGNORE all these posts telling you of fixes, many alter it but NONE fix it, its a hardware fault.

If its less than 1 Year old take it to Apple they will exchange it for a refurbished one, if its more and you have Vodafone insurance take it to them. if you dont, then you are stuck, downgrade to 3.13 or chuck it.

I sold my replacement, bought a Win7 phone and its the best thing I ever did, its marvelous compared to the iPhone.

From the many pages of posts, it seems that there is general agreement that this problem is caused by interaction of both software and hardware. Software because there was not a problem before version 4. Hardware because it affects the iPhone 3 GS and not the iPhone 4.

After reading some of the posts by minionedriver and icehacker, I think it is quite possible that the culprit(s) could be mobilewatchdog (not the kid tracking software with the same name) and something called Springboard. Some posts, listed below, are 2-years old and discuss problems with mobilewatchdog, so this is apparently not a new problem. The first post leads one to believe that the timer that checks temperatures can be adjusted to check every 10 minutes instead of every two minutes.

If I found these posts, surely Apple can as well. One of them gave me the impression that the heat buildup and lack of thermal information before the reboot might actually damage one of the thermal sensors. That could mean that, while the initial problem was caused by the software update, it can only be fixed by replacement hardware. Here are those posts in no special order:

http://xsellize.com/topic/69743-mobilewatchdog-and-thermalmonitor/

http://www.hackint0sh.org/f136/9570.htm

http://modmyi.com/forums/general/740331-does-anyone-know-how-patch-mobilewatchdo g-increase-timeouts.html

http://www.twiphone.com/2008/12/01/how-to-repair-apple-logo-screen-of-death-endl ess-boot-without-ssh-access/

http://iphonefreakz.com/2008/09/01/apple-logo-of-death-solution-swod/

Lauren!
Do you know where the thermal sensors are located? On the main board or are they part of the battery?
If they are part of the battery, then a newer, iOS4 capable replacement battery could fix the issue. Of course if the sensor is on the main board, then replacing the phone is the only option.

Sorry, sb0611, I don't know how many there might be or where they might be located. A look at a breakdown I found of individual components does not list a thermal sensor nor do any of the components list a thermal sensor being a part of that component.

However, I did find a picture of a temperature warning being displayed on the screen along with instructions saying to let your iPhone cool down before using. Also included in the article were recommendations not to use your iPhone when the ambient temperature exceeded 113°F (45°C) and not to use the GPS or iPod portion if the ambient temperature exceeded 95°F (35°C).

Is there anyone having this problem who does not believe that the cause is somehow temperature related?

Has anyone really fixed the problem with a software change including reverting back to 3.1.3?

If the answer to these is 'NO,' the theory would explain everything: The update to iOS 4 actually damaged the sensor in a confined batch of iPhone 3GS' so the only fix is replacement.

That would also explain why Apple will replace your phone, but only if you complain often or in the manner as those above who have been successful. Due to the cost, they don't want to announce a replacement program.

Lauren,

Thanks for your quick answer. I myself have a factory unlocked 3GS running 3.1.3 and I have been reluctant to move to iOS 4.x due this persistent reboot issue (I live in a country where there is no Apple support).

I believe you are right, that it's a software driven (iOS 4) hardware issue (thermal sensor and/or battery) and the culprit could (at least) one of three things:

1. The thermal sensor gets fried during or after the iOS upgrade process. If the sensor is integrated with the battery, it would be a relatively easy replacement fix (e.g. ifixit.com).

2. The thermal sensor is on the main board and gets fried during or after the iOS upgrade process. That would be much bigger replacement issue and is consistent with Apple's behavior from what I have seen in this thread.

2. The thermal sensor under iOS4 can't fully communicate with iOS4 incompatible batteries. I know some of the older 3GS batteries could result into error 29 problems when upgrading to iOS 4.x, but newer replacement batteries seem to fix that problem and are compatible with the new iOS.

Some clarification from Apple would be nice 🙂

Is there anyone that can confirm this? My phone has been rebooting in standby, the audio turns completely off, I get white noise at full volume instead of ringtones, and the mic turns off with the audio so I cannot answer a phone call. Do I really need a new phone? Or is there a fix? I have tried restoring, but that did nothing.

I was and am reading this thread on a daily basis since my iphone 3GS was experience the same problems and was already out of warranty (~13 months old).

I tried several of the suggested "fixes", none really worked in the long run. I am running 4.1 and the reboot happened, most of the time when the signal was weak.

I replaced the battery last week (myself) and the reboots are completely gone (not a single reboot since then, phone running now for almost 7 days, even with excessive 3g and edge data use).

So IF the culprit is a sensor, it could have been on the battery.

My crash logs contained a lot of "lowBatteryLog" crashes before replacing the battery. With the old battery I realized that very often just before crashing the battery showed to be completely empty, after restarting the phone the battery was up to 70% and more again.

Maybe this helps somebody...

I have never had a problem with the battery, on any iOS version. I am currently running 4.2.1 and it was only the latest update that caused all these problems. I would like to know if there is a solution.

Just a post to say I have exactly the same issue.

What I don't understand is why it's such an intermittent problem. I've had weeks now where I could make long calls with no crashing, and I'd thought the problem had resolved when I upgraded to 4.1.2 (or whatever update we're on) and/or talked to the people at Optus. The Optus woman had me run through a bunch of stuff which I can't remember now. I had previously talked to someone at Apple (I'm well out of warranty, having bought my phone 18 months ago) who wanted me to restore as new. I decided that was too much of a PITA to do that, but after today when my phone again crashed while I was on a call, I'm rethinking that advice.

Yeah I upgraded to 4.2.1, it worked for about half an hour, which was the most I could get out of mine, then back to rebooting. Every 5 mins for me weather I was calling or playing a game or surfing the net.

Followed advice on here on replacing mobilewatchdog. IT WORKED! You have to bloody ja!lbreak (and on 4.2.1 new bootrom like mine its a tethered one), which I really didn't want to do, but otherwise you cant access the root directory.

Anyway, look up replacing the mobilewatchdog as that is what's causing the problems. No other "fixes" worked like turning off this or that.

This thing is the faulty program which doesn't report the battery temp properly and reboots. Replacing it with the one from 3.1.3 has fixed the problem for me.

Dunno why crapple don't fix it themselves.

INITIALIZE IOs421 - same Problem

Hi everyone,
I am in the UK and new to this forum. I have spoken to the retailer from whom I got the phone 6 months ago (Tesco) and they just tell me to return it to their user support department by post and they will "sort it".

They played dumb when I told them it was a well documented fault!

PROBLEM RESOLVED
I to have had the same problem as every one else on both my phone and my wives phone after upgrading to OS4.1 But I have finally resolved the problem and I would like to share it with everyone else and hope this helps others.

Ok after trying everything nothing worked but I started to read on some forums that by changing the battery everything goes back to normal, so being desperate I thought I’d give it a go so I went to EBay and found two original batteries and I bought them.

Now the thing is because I was inpatient thinking this may fix it I pulled my phone apart removed the battery and tried two of the 3g batteries I had to see what happens.
I can tell you it doesn’t work the phone started to do continuos reboots so their must be a difference in the chip they have otherwise they look identical.

I figured I’ll have to pull it apart and put my original battery back in for now until I get the new ones and to my surprise no more problems all my problems have disappeared I did the same to my wives phone I took the battery out for five minutes put it back in and ones again problem solved.

So the problem is somehow the operating system got corrupt or didn’t install properly or something like that but because I don’t know much about Apples platform I can’t really say. If this was a windows based phone I would conclude by saying somehow the Bios got corrupt and so it needs a reset, well I have had this problem many time before on widows based Desktops and the only way to fix it is by switching the power off and removing the bios battery for a few minutes while pressing the power button do discharge any capacitors that are still holding power. These phones are impossible to completely reset because their batteries are built in and really this was my biggest concern when I bought the phone I always thought what do you do if your phone freezes how would you reset it you cant simply pull the battery out.

PROBLEM RESOLVED
I to have had the same problem as every one else on both my phone and my wives phone after upgrading to OS4.1 But I have finally resolved the problem and I would like to share it with everyone else and hope this helps others.

Ok after trying everything nothing worked but I started to read on some forums that by changing the battery everything goes back to normal, so being desperate I thought I’d give it a go so I went to EBay and found two original batteries and I bought them.

Now the thing is because I was inpatient thinking this may fix it I pulled my phone apart removed the battery and tried two of the 3g batteries I had to see what happens.
I can tell you it doesn’t work the phone started to do continuos reboots so their must be a difference in the chip they have otherwise they look identical.

I figured I’ll have to pull it apart and put my original battery back in for now until I get the new ones and to my surprise no more problems all my problems have disappeared I did the same to my wives phone I took the battery out for five minutes put it back in and ones again problem solved.

So the problem is somehow the operating system got corrupt or didn’t install properly or something like that but because I don’t know much about Apples platform I can’t really say. If this was a windows based phone I would conclude by saying somehow the Bios got corrupt and so it needs a reset, well I have had this problem many time before on widows based Desktops and the only way to fix it is by switching the power off and removing the bios battery for a few minutes while pressing the power button do discharge any capacitors that are still holding power. These phones are impossible to completely reset because their batteries are built in and really this was my biggest concern when I bought the phone I always thought what do you do if your phone freezes how would you reset it you cant simply pull the battery out.