Symptoms
- Security or key-shaped icon lit or flashing
- Engine cranks but won't start, or won't crank at all
- May happen with a specific key or after a battery replacement
Likely causes
- CommonChip in the key fob not being recognizedInterference, a weak fob battery, or a damaged chip can prevent recognition.
- CommonUsing a spare or newly cut key that wasn't programmedSome keys need to be programmed to the car's specific immobilizer system.
- CommonWeak key fob batteryA dying battery can be too weak to transmit the signal reliably.
- PossibleRecent battery disconnect or jump start confusing the systemSome systems need a relearn procedure after the car battery is disconnected.
- Less commonFaulty immobilizer module or antenna ring around the ignitionMore involved and usually needs a dealer or locksmith to diagnose.
What to do
- Try a different key for the car if you have a spare, to see if the issue is key-specific.
- Replace the key fob battery if it's been a while, then try starting again.
- Hold the key very close to the ignition switch or start button, since some systems need close proximity to read the chip.
- Check your owner's manual for any reset procedure after a battery disconnect.
- If using a spare or newly cut key for the first time, it likely needs to be programmed by a dealer or locksmith.
- Have the car towed to a dealer or automotive locksmith if no key works and the light stays on.
Tools and parts
Key fob batterySearch: “correct battery size for your key fob”
When to call a pro
See a dealer or automotive locksmith if no key starts the car, since immobilizer issues often need specialized programming equipment.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.