P0633Immobilizer Key Not Programmed ECM/PCM
- Generic OBD-II code · Powertrain
- How the car detects it
- The immobiliser couples the engine module to the immobiliser control module (GM body module, Chrysler SKIM/WCM) through a secret key and a challenge-response exchange – 'key' here means these security data, not the ignition key. P0633 means the engine module has not learned this secret key yet. At GM and Saab the code is set automatically whenever the engine module enters learn mode, for example as a new part, and clears after a successful learn and engine start; it is only a real fault if learn mode does not end, often because the engine fails to start for another reason. Chrysler calls it 'SKIM secret key not stored in PCM' and fixed false settings on the 2012–13 Grand Voyager 2.8 diesel by software. The engine does not start or dies after one or two seconds; the security lamp, not the check engine light, comes on.
- What you may notice
- Engine does not start or dies immediately
- Security or immobiliser lamp on or flashing
- Code present after engine module replacement until learned
- Sometimes immobiliser communication codes
- Likely causes
- LikelyEngine module replaced, immobiliser not learned
- PossibleLearn procedure aborted or learn mode not exited (no start for another reason)
- PossibleCommunication fault to the immobiliser module
- RareEngine module software fault (false setting)
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.