The iOS 4.0.2 firmware update has been released by Apple today and its downloads are available too. You could update iPhone 3G/3GS to iOS 4.0.2How to Update iPhone 3G, 3GS to 4.0.2 automatically or manually using iTunes. So if you want to update your iPhone 3G or 3GS to iOS 4.0.2, then here is how to do it.

Automatically

1. Download iTunes 9.2.1 from here.

2. Connect your device to the computer.

3. Now you will be shown a message when iTunes come up.

4. Click the ” Download and Install ” button to update iPhone 3G/3GS to iOS 4.0.2.

Manaully

1. Download iTunes 9.2.1 from here.

2. Download iOS 4.0.2 firmware for iPhone 3G and 3GS from here.

3. Connect iPhone 3G/3GS to PC.

4. Choose your device from the left side list.

5. Press the Shift key(in Windows) or the option key(in Mac OS X), click on the Restore button.

6. Now browse to the iOS 4.0.2 firmware update and select it.

That’s it! You have successfully updated your iPhone 3G/3GS to iOS 4.0.2.