This is due to various causes, but usually has to do with the DFU mode.
Followed to the letter the guidelines to put your iPhone in DFU mode.
Clears x12220000_4_Recovery.ipsw is in your iTunes folder.
Make sure the firmware you are using is right for your iPhone (2G or 3G)
Problem: I am in DFU mode with the iPhone but I keep seeing errors, Error 1604, 1602, 1601 (160x). What is the problem?!
- Make sure you use the correct version of firmware (the 2G or 3G on the model of your iPhone).
- Restart your computer and try again.
- Try other computers or different operating systems (Windows or Mac) .- This is what worked for me.
- Try other USB ports
- Uninstall and reinstall iTunes.
You have your other solutions, please share them with us.