Immobiliser (security) light
The engine immobiliser: a transponder chip in the key must be recognised before the engine will start. The light comes on briefly while the key is checked, and on many cars blinks while the car is off to show the system is armed. Lit or blinking when you try to start means the key has not been recognised, or the system has a fault.
Yellow / amberRed
Not defined by regulation: a maker convention
What to do
Blinking with the car switched off is normal: Toyota and Nissan both describe it. If it stays on or blinks when you try to start, check it is your own registered key and that it is inside the car, switch off and try again; Mazda says contact a dealer if the engine will not start after 3 or more tries, and Kia says a weak key battery can cause it. If a red security light flashes while you drive (Mazda), do not switch the engine off — it may not restart — and drive to a dealer. Take every key when the system is repaired: they are reprogrammed.
Makes differ: what this light means on your car, the other colours it may use for the symbol and what the car wants you to do are set by the manufacturer, so your car's owner's manual is the authority.
- Symbol
- Car outline with a key inside it
- Also called
- Security light; Immobilizer indicator; Anti-theft light
- Colour
- Yellow / amber or Red
- Standard
- None — a maker convention, described here from 4 makers: Kia, Mazda, Toyota, Nissan
Where makes differ
Mazda's security indicator is red. Kia's immobiliser indicator is amber and, with a smart key, lights for 30 seconds; lit for only 2 seconds or blinking means have it checked. Toyota and Nissan call it the security indicator and flash it after the car is switched off to show the system is working.
Not defined by regulation: a maker convention
Neither US FMVSS 101 (Tables 1 and 2) nor UN Regulation No. 121 lists this light, so no rule fixes its symbol or its colour. What follows is what the makers cited below say; other makes, and other model years of the same make, may draw it differently.
Neither FMVSS 101 nor UN R121 lists an immobiliser tell-tale.
Related lights a regulation does define
Other yellow / amber maker lights
All yellow / amber dashboard lights, regulated ones included
Other red maker lights
Sources
No regulation defines this light, so it is described from 4 carmakers' own manuals or owner pages, each fetched and checked on the date shown:
- Kia: Kia UK — Dashboard warning and indicator icons (PDF) (Immobiliser Indicator) — Lights until the engine starts; with a smart key it lights amber for 30 seconds. Lit for only 2 seconds or blinking: have it checked. It also blinks if the smart key battery is weak. checked 2026-09-28
- Mazda: Mazda owner's manual, Mazda3 (Europe, 8HC2-EO-19A) — Security Indicator Light (Security Indicator Light) — If it flashes continuously while driving, do not shut off the engine — it will not restart; after 3 failed starts contact a dealer; bring all keys to be reprogrammed. The manual's indicator table draws the light in red. checked 2026-09-28
- Toyota: Toyota USA — Warning lights (MyToyota owners pages) (Security Indicator) — The engine immobilizer stops the engine starting with an unregistered key; the indicator flashes after the engine switch is turned off to show the system is operating. checked 2026-09-28
- Nissan: Nissan UK owner's manual, 2023 LEAF — Security indicator light (Security indicator light) — Blinks with the power switch in LOCK, OFF or ACC to show the NATS immobilizer is working; stays on in ON if NATS is malfunctioning. checked 2026-09-28
Written in our own words; the makers' pages cover their own models only.