P0633: Immobiliser Key Not Programmed — Engine Control Module
Do not keep driving
The vehicle will crank but not start. Needs a franchised dealer or a qualified auto-locksmith with the correct equipment, and you will need proof of ownership. If a control module was recently replaced, that is the cause and the programming was simply not completed.
What this code means
The engine module has no valid key programmed to it, so it will not authorise the engine to run. Distinct from P0513, which means a key was presented and rejected — this means the module has no key on record at all, which is the state a new or replacement module arrives in.
It therefore points at recent module work rather than at a failing key. A module fitted without immobiliser programming produces a vehicle that cranks and will not run, with everything else apparently healthy.
Likely causes
Start here
- Module not coded to the vehicle · specialist
- Key not correctly programmed · specialist
- Second hand module locked to another vehicle · specialist
Less common
- Faulty immobiliser control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
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