What does it mean?
P0633 is a generic code trouble code defined as Immobilizer key not programmed -ECM/PCM . It will be triggered when the signal coming from the key doesn’t match what the PCM (Powertrain Control Module) expects to get. To understand the meaning of the code, we’ll first have to explain what the immobilizer key is and what it does. Most modern cars have one or more anti-theft functions integrated into their electronics, which prevent them from being entered into or stolen easily.
Some of the features include remote locking, an alarm, and, most importantly, the immobilizer. This device is usually integrated into the vehicle’s PCM and prevent’s it from being turned on until it receives an appropriate code. This code, which acts as a password, is, in most cases, digitally inscribed into the car keys.