Please help, my Saturn Vue 2003 SUV engine was changed and my mechanic finding it difficult to start the engine, we have scanned and said communication error in ECU, we decided to change the ECU it's same thing. The previous engine had gasket burnt and I decided to change engine but with all the old wires. But still not start, we do not have remote, we only have key.

Can someone help on how to reconfigure or reprogramming the security code without remote or any other help that think may be relevant to make the vehicle start.