A Mazda key will not turn in the ignition for three main reasons: a problem with the physical key code, a tight steering column or a faulty ignition switch. In each case, the key is not connecting properly with the ignition switch.
Mazda Key Code
The Mazda key can contain a computer chip in its head specifically coded to communicate with a particular vehicle. Starting the ignition requires the correct code. A key inserted without the correct code may not turn at all or may only crank forward without starting.
Steering Wheel Lock
A steering wheel has a lock mechanism to prevent the key from turning in the ignition, a security device to prevent theft. To start the ignition, pull and hold the steering wheel to the right or left before you turn the key.
Tires Turned Tight
A key may not turn the ignition switch when you park the car on a hill with tires turned to the curb or out too tight. This position places pressure on the locking pin in the steering column and prevents it from moving. Rock the steering wheel left and right to loosen the locking pin and start the car.
Lose Ignition Switch
The ignition switch and starter can become loose and slip so the key fails to make correct contact. You can try to push the key in as you turn it. The starter may require replacement or at least tightening.