Will not start after replacing the ignition?

Hi,

It sounds like the immobilizer isn't recognizing the new key. What needs to be done is an encrypted key code registration. However, that does require a scan tool that can communicate with the ECU. All of the old codes will need to be deleted and the new one registered.

https://www.2carpros.com/articles/how-to-reset-a-security-system

Before we jump to that, tell me if the immobilizer light is staying on at all times. Also, let me know if you have a scan tool that can communicate with the ECU/PCM or if you have access to one.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Joe

Hi,

Honestly, that is a good one! Vehicles are becoming so complex, it is hard to even determine what could have caused the 2nd key to work. LOL

As far as the Mitsubishi, I attached a pic below for you to look at below. The ignition key has a built-in transponder. The keyring antenna is installed on the steering lock key cylinder. The antenna is part is on the ignition lock cylinder. At this point, the old key doesn't match. That is why it needs to be programmed.

Let me know if that makes sense. LOL

Take care and keep me updated or let me know if you have questions.

Take care,

Joe