0003 Xbox 360 secondary error code | Three red rings guide
What's gone wrong?
First and foremost the 0003 secondary error code is a problem with the power inside your console. The console gets power to critical areas, but still has an issue somewhere causing this 0003 error. There are a few causes but two of them are the most common. So let's dig deeper shall we?
Check your power brick!
The Xbox 360 power brick is much more sophisticated than most people realize. This also means it tends to fail more often then plain generic power cords. Try replacing that power brick with a working one and see what happens. If the 0003 error code clears out with a new power brick, you've found the problem! There is also a chance you are using an incorrect brick with your console version. There is a handy guide on which power supply your Xbox 360 needs here. Check that out and see if you need to switch out to a different one.
Possible user caused issues
Honestly, the most common cause for a 0003 secondary error code tends to be people related. Reflowing the CPU or GPU chips on the motherboard can blow components off the rails and even the motherboard itself. If you attempted to repair another RROD error code issue with a reflow and ended up with the 0003 secondary error afterwards, you more than likely have a small capacitor missing somewhere. If you can, find an identical motherboard (Or a good picture of one) and compare with your own. See any missing components? If so, replace them!
Advanced issues
If all else fails, this could be a much more advanced problem. For instance, Mosfets on the motherboard could be malfunctioning. If mosfets go bad, they can easily cause the 0003 error code on an Xbox 360 console. For the vast majority of people this would be a problem that can't be fixed. You may want to consider finding a replacement motherboard like one of these
