Car Alarm vs Immobiliser: What's the Difference?
A car alarm detects intrusion and triggers an audible alert; an immobiliser prevents the engine from starting. Both serve different purposes — and the best protection combines both.
A car alarm is a perimeter protection system. It monitors for intrusion — door/boot opening, glass breakage, motion inside the cabin, tilt or shock — and responds with an audible siren and flashing lights. The goal of an alarm is deterrence: to draw attention to the theft attempt and discourage the thief from continuing.
An immobiliser is a prevention system. It stops the engine from starting without authorisation — regardless of what happens before or after the car is entered. A quality CAN-bus immobiliser like IGLA means the car cannot be driven away even if a thief has successfully unlocked the vehicle and sits in the driver's seat with a cloned key.
The key distinction: an alarm does not stop the car from being stolen. An experienced thief with a good relay setup can unlock a car, disable a basic alarm (by pulling the battery or using a jammer) and drive away in under two minutes. An immobiliser removes the ability to drive, full stop.
The recommended layered approach for high-risk vehicles in Melbourne is: IGLA CAN-bus immobiliser (stops the engine) + Compustar 2-way alarm (deters and alerts) + ImmoTrack GPS (enables real-time recovery if the vehicle is towed). Each layer addresses a different threat vector.
Common questions.
Is an immobiliser or alarm more important for stopping theft?
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An immobiliser is more important for actually preventing the car from being driven away. An alarm is important for deterrence and notification. For comprehensive protection, we recommend both — starting with IGLA as the immobiliser foundation.
Can a thief disable an alarm without disabling the immobiliser?
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Yes. An alarm can be defeated by pulling the backup battery, using a signal jammer or by working quickly enough to accept the noise. A correctly installed CAN-bus immobiliser like IGLA is not affected by alarm tampering — they are independent systems.
What we install.
Learn more.
IGLA is a CAN-bus PIN immobiliser that integrates into your vehicle's factory electronics and prevents the engine from starting without a driver-set PIN — even with a cloned or relayed key.
A CAN-bus immobiliser integrates directly into a vehicle's Controller Area Network to prevent engine start at the software level — unlike basic wire-cut immobilisers that can be bypassed by finding and bridging the cut wire.