Security / Immobilizer Indicator
Flashing with the car off: the immobilizer is armed (normal). Lit while driving or at startup: the key is not recognized.
What it means
A slow flash when parked is the anti-theft system doing its job. If the light is on or flashing when you try to start — and the engine cranks but will not fire or will not crank — the immobilizer does not recognize the key, usually due to a dead key-fob battery or a failed transponder.
Can you keep driving?
If the light only flashes when the car is locked, everything is normal. If the car will not start, try a spare key or hold the fob against the start button/column (see your owner's manual) — a dead fob battery is the usual cause.
What to do now
- 1
Try the spare key first.
- 2
Replace the key fob battery — on push-button cars, hold the fob directly against the start button to start with a dead battery.
- 3
If no key works, the immobilizer module needs dealer or locksmith diagnosis.
Likely causes
- • Normal armed state (flashing when parked)
- • Dead key fob battery
- • Failed key transponder or antenna ring
- • Aftermarket alarm/remote-start conflict
Typical fix cost
$3–$10 for a fob battery; $50–$250 for key reprogramming or a new key
Ranges reflect mainstream US parts-and-labor pricing; your vehicle and region will vary.