I have a 06 Chevy impala my car key broke in two pieces so I bought a new one. My key has a chip in it as well. I programmed the key to my car but when I try to start car anti theft comes on but car d

To program any new key you need a working master transponder key, that you can insert into the ignition and turn to the on position. If you can't do that because your existing master key is broken, there's no way to add a new duplicate key or program a new master.

Have a standard key cut ( a regular key with no plastic .. just all metal) Get the broken half of your old key that has the plastic and hold the plastic against the all metal key ... Insert an existing programmed working key into the ignition cylinder. 2. Turn ignition to the ON position for 5 seconds, then back to OFF position. 3. Remove the existing key and within 5 seconds insert new key and turn it to the ON positiion for 5 seconds. 4. Turn key OFF then back to ON. The key is now programmed. Start vehicle to test key.