Cause
Faulty immobiliser antenna ring
The coil around the ignition barrel that powers and reads the key's transponder, faulty so the key cannot be identified. The transponder has no battery — the ring energises it inductively and reads its reply — so a broken ring leaves a perfectly good key unreadable.
The symptom is a vehicle that cranks and will not run, with the immobiliser warning showing, and it is easy to mistake for a dead key. Trying a second key is the fastest test available: if both fail, the fault is on the vehicle rather than in either key.
The ring's lead is what usually breaks. It runs from the barrel through the steering column, where it is flexed every time the wheel moves and disturbed by any steering or airbag work. Check the connector at the column and the lead where it enters — and note that holding a spare key close to the barrel sometimes works around a weak ring, which is a useful confirmation as well as a way to move the vehicle.
Typically specialist work. Needs equipment or training most home workshops do not have.
Some of these codes mean you should stop driving
2 of the 2 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (2)
Codes where this is a likely explanation first, rather than merely a possible one.
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.
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