P0633
Immobiliser Key Not Programmed
The immobiliser system rejects the current key because it is not programmed to this vehicle. Engine start is inhibited.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Common causes
Ordered by how often each turns out to be the cause.
- Key not programmed to vehicleCommon
- Immobiliser module faultLess likely
Parts involved
- Immobiliser
- ECM
P0633 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.