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Immobiliser / Key Warning
Your car doesn't recognise the key — it may not start or could cut out.
What it means
A red or amber icon of a key, a car with a key, or the word KEY / SECURITY. The immobiliser system can't verify the key. The engine may crank but not start, or may cut out unexpectedly. On push-button cars it can mean the key fob battery is flat or the car can't detect the fob.
What to do
- 1If using a spare key, try the main key — spares sometimes lose their coding.
- 2Hold the key fob right against the start button (or steering column on older cars) — the battery may be weak.
- 3Replace the key fob battery — it's often a CR2032 and costs a few pounds.
- 4If none of the above works, the key may need reprogramming or the immobiliser ring/antenna has failed.
Likely causes
- •Flat key fob battery
- •Key not recognised (damaged transponder chip)
- •Faulty immobiliser ring around the ignition barrel
- •Interference from other key fobs or electronics
- •Car battery low causing immobiliser to glitch
Rough UK cost
Key battery: £3–£8. Reprogramming: £50–£150. New key: £100–£400. Immobiliser ring: £150–£400.
Prices are a guide only — always get a written quote before any work.
Heads up: Carautonomy is for general guidance only. If your car is behaving oddly or any red light is on, get it inspected by a qualified mechanic.