Diagnostic guide
Car Says Key Not Detected
The key is with you, but the vehicle says it cannot find it.
Photo: Barry A / Unsplash
Start here
Check the spare and your owner’s manual for the vehicle’s low-battery or emergency-start instructions.
Our method
- Check the simplest cause.
- Compare a working spare when possible.
- Verify before ordering a replacement.
A key-not-detected warning does not always mean the entire key has failed.
Try the simple checks first
- Use your spare key if available.
- Replace the fob battery with the correct type.
- Remove other electronic devices or keys from immediately beside the fob.
- Consult the owner’s manual for the manufacturer’s emergency-start procedure for a low/dead fob battery.
Important distinction
The remote buttons and the immobilizer/start authorization system can involve different components. A fob can sometimes unlock doors yet still fail to authorize starting—or the reverse.
If both keys are not detected, or the warning persists with a known-good key, vehicle-side diagnosis may be needed.