Error Code P0633 is defined as Immobilizer Key Not Programmed – ECM/PCM. This is a generic trouble code, meaning it applies to all cars equipped with the OBD-II system, particularly cars made since 1996 up to present. This includes cars from, but not limited to, Cadillac, Chevrolet, Chrysler, Dodge, GMC, and Jeep. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.
Then Error Code P0633 is stored, this means the PCM (powertrain control module, also known as ECM or engine control module in other 1998 Land Rover Discovery Series I makes) has determined an immobilizer key that it doesn’t recognize.
The job of the immobilizer key is to key your 1998 Land Rover Discovery Series I safe from theft and eliminate the need to use an actual metal key into the door lock cylinders, or ignition cylinder. A transponder powered by a small battery is equipped into the immobilizer key fob. When the key fob is inside a certain distance from your 1998 Land Rover Discovery Series I , a transponder emits a signal to the PCM and other controllers. Usually, when a transponder signal is received, the doors are unlocked, and your 1998 Land Rover Discovery Series I ’s push-start button is activated. When the immobilizer key is moved away from the doors, the door locks automatically, and the push-to-start button will be deactivated.
Every immobilizer key emits a unique signal. For onboard controllers to recognize this signal, they must be programmed appropriately. The PCM and security control module are both responsible for engine starting, while the BCM (body control module) is responsible for the functions of door and trunk lock/unlock.
Thus, this being said, when PCM or immobilizer is replaced, it must be programmed.
If the PCM is unable to recognize the immobilizer key, and your 1998 Land Rover Discovery Series I entry or start-up is attempted, Error Code P0633 will be triggered, simultaneously activating the Check Engine light. The immobilizer key transponder signature is compared between the PCM and other controllers, each time the security system is activated, and self-test function is energized.
Other related diagnostic code may be present.
Possible Causes
Dead battery discharged for an extended period of time can cause the PCM to lose programming, which means it needs reprogramming.
Because of the delicate nature of certain parameters that must be programmed to the PCM (mileage, VIN), reprogramming equipment access is limited only to qualified personnel. Thus, without the tool to reprogram the troubled controller, successful repair for this problem is highly unlikely.
Though this code is usually caused by controller failure, or some controller programming error, battery problem with the transponder or immobilizer key can also cause this issue.
For a more accurate diagnosis, you need a diagnostic scanner and reliable 1998 Land Rover Discovery Series I information source for this code. Find a TSB that matches with your 1998 Land Rover Discovery Series I make and model, symptoms of the problem, and code stored, as this will help you to point to the right direction.
By connecting the diagnostic scanner to your 1998 Land Rover Discovery Series I diagnostic port, you can see whether the PCM (and other controllers) are recognizing the immobilizer key. This information is typically shown as a yes or no, without a specific transponder description. If the PCM is not recognizing the immobilizer key, then you can suspect the battery is dead in the key fob, or the wrong immobilizer key is being used.
If an inadvertent immobilizer key yes signal is shown on the scanner display, you can suspect that the PCM may have been replaced without programming it to match with your 1998 Land Rover Discovery Series I . If this is not the case, then you can suspect failed PCM problem or programming error.
In some cases where reprogrammed, aftermarket, replacement controllers and immobilizer keys may be purchased, it is important to provide the parts vendor with the mileage and VIN of your 1998 Land Rover Discovery Series I , as well as its secondary (factory programmed) immobilizer key.
Replacement of any component of VSS (1998 Land Rover Discovery Series I security system) or controller usually requires reprogramming.
Since this code keeps your 1998 Land Rover Discovery Series I from starting, it’s a serious condition.
Unfortunately, though, diagnosis and resetting of the code will not always fix the problem, as it requires reprogramming. Vehicle ID, mileage, and anti-theft settings are all required to reset before your 1998 Land Rover Discovery Series I can be operated.