Aftermarket vs factory car alarms: is it worth upgrading?

“My car already has an alarm” is the most common reason people give for not needing us. It is a completely reasonable thing to think, and the answer is more specific than “ours is better”.

What your factory alarm is good at

It is not rubbish. Modern factory security is genuinely decent at the job it was designed for:

• Detecting a door, bonnet or boot being opened without the key
• Detecting the ignition being tampered with
• Making a noise and flashing the lights
• Immobilising the engine against hot wiring

For twenty year old theft methods, that is a solid package.

The gap

The problem is that the most common way a modern car gets stolen involves none of those things happening.

In a relay attack, the doors are opened with what the car believes is your key. The ignition is started with what the car believes is your key. Nothing is forced, nothing is tampered with, nothing is hot wired.

Your factory alarm stays silent because, as far as it can tell, you are getting into your own car. It is not failing. It is being told the truth by a lie.

That is the gap, and it is the entire argument for an aftermarket system.

What a good aftermarket system adds

It tells you, not the street. A siren relies on somebody hearing it and caring. A Pandora system sends the alert to your phone, wherever you are.

Sensors the factory did not fit. Tilt sensors for wheel theft and jacking. Movement sensors inside. Glass detection. Most factory systems cover far less than people assume.

Relay attack awareness. Systems designed for how cars are stolen now, rather than how they were stolen when the car was designed.

A second, independent immobiliser. Separate from the factory one, and hidden where a thief would not know to look.

It works with what you have. It does not replace the factory alarm, it sits alongside it. You keep everything you already had.

When we would tell you not to bother

We are not going to pretend everyone needs this.

If your car has a traditional key you physically turn, and it is not a model with a known weakness, the relay argument does not apply to you. Your risks are different and possibly lower.

If the car is worth very little and there is no strong parts market for it, the maths may not work. We will say so.

If your only worry is theft of the whole car, an immobiliser may be a better and cheaper answer than a full alarm. Different job, often the right one.

The simple test

Go and try your door handle with the key in your pocket. If the car unlocks, your factory alarm cannot tell the difference between you and a relay device.

That is the whole question, and it takes ten seconds to answer.

Tell us the make, model and year and we will tell you honestly whether you need us.