Electrical issues with Mazda3 '07

I have personally seen this happen before and it was all caused by a fault in the battery. Intermittently an internal short would happen inside the battery which would cause the vehicle to die. When the car would re-start the clock would reset and radio presets would be lost.

If this problem didn't exist before you replaced the battery earlier this year I would recommend replacing the battery again.

Also, this kind of failure is not likely to show on a traditional battery test so getting this battery covered under warranty (if it has one) may be difficult.

In the future keep in mind that NEW stands for

• Not
• Ever
• Worked

A new part doesn't always mean a fully functioning part.

Check your terminal connections, make sure they are clean and tight, then get the battery tested anyways.

This is similar behavior to a loose/bad ground although losing the remote programming is strange.

A proper battery tester will do tests on the battery with and without a load, you could have a bad cell or many other issues internal to the battery. Battery tests are usually free at parts shops and some service shops that sell batteries. It of course only works correctly when the battery is grounded correctly so there's a bonus test in there.

Your keys don't automatically reprogram themselves though so if they lost power and were never reprogrammed, that's a separate issue.