Car Immobilisers

An Immobiliser is an electronic device designed to stop a car from being driven away without the correct key. In other words it prevents the vehicle from being hot-wired.

Whilst most European cars have had them fitted as standard since 1998 due to legislation, it is still not even a basic requirement here in NZ. Even our cousins across the ditch made it mandatory for new vehicles to have them installed back in 2001 and the statistics from both Australia and Europe prove that they are effective.

After market Immobilisers

It is my opinion that factory installed Immobilisers are more effective then aftermarket systems, the main reason for this is the installation, if the Immobiliser is easy to find then it is normally easy to by-pass. Our consumerist nature to hunt in search of the cheapest price results in an installer trying to fit the system in the minimum possible time, this in turn leads to short cuts being taken and an installation that is not very effective.

Aftermarket Immobiliser Options

There are three basic options for aftermarket Immobilisers, all of them should immobilise the vehicle within 40 seconds of the engine being turned off.  The first is a transponder Immobiliser which allows the vehicle to start only if the transponder tag or chip is in proximity of the ignition barrel. The tag normally attaches to the key ring like the above photo.

The next type is the touch key Immobiliser which requires the touch key to make contact with the receiver pad before allowing the vehicle to start, this is not as nice to live with as the transponder Immobiliser as a conscious effort to disarm the system is required.

The third type is the remote Immobiliser which disarms the system when the remote is pressed, this is the most common type found in New Zealand and usually comes as part of a car alarm.

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11 Responses to Car Immobilisers

  1. Pingback: NZSA 3 Star or Thatcham CAT 2 | Obsessive Vehicle Security Blog

  2. Eddie Stanley says:

    “It is my opinion that factory installed Immobilisers are more effective then aftermarket systems, the main reason for this is the installation, if the Immobiliser is easy to find then it is normally easy to by-pass.”

    But is it not the case that factory immobilisers would always be installed in the same place for a given make/model? Therefore once a thief has stolen a particular car once, stealing it again should be trivial?

  3. Julian says:

    Hi Eddie,

    I understand your point, but given that factory immobilisers are generally built into the ECU on most new cars it is not a simple case of being able to by-pass them. Sure the vehicle may be at risk from a good professional thief with the right equipment but it certainly puts the system beyond the capability of a opportunist thief.

    The statistics I have come across support my view point: Read this article on

    “According to Subaru New Zealand, the marked Subaru range has not seen one theft here since its March 2003 introduction.”

    On Subarus in Australia, the unrecovered theft rate initially fell four years ago by 93% and has stayed much that way since.

    Of course I accept that the Microdots are also a big reason for the drop in Subaru theft but on the whole it would suggest that the Immobiliser is effective. Obviously the more security there is to get past then the harder it would be to take the vehicle. An upgrade alarm on top of a factory immobiliser would be my preference.
    The main point of the Blog is that the Immobiliser is only as good as the install, and on the whole most of the “after market” installs I come across are not that flash!

    Please read my posts titled NZSA 3 Star or Thatcham Cat 2? and Even the Car thieves Agree…

  4. Pingback: Upgrade Alarms | Obsessive Vehicle Security Blog

  5. Ewen says:

    Hi Julian, could you please tell me what it means when the alarm mention to have dual immobiliser?

    great job with reviewing the alarm for us non-technical persons,


  6. Julian says:

    Hi Ewen,

    Good question, it seems I completely overlooked explaining that part of it!

    An Immobiliser cut is simply a wire in the vehicle that when cut prevents the car from running. For example if I cut the wire going to the starter motor then it will get no power and prevent the car from starting. Other immobiliser cuts could be the fuel pump, ignition, ECU or various other circuits which can stop a car from running.

    When disarmed the immobiliser re-connects the cut (or cuts) and allows the vehicle to start as normal.

    The term “dual immobiliser” simply states that two immobiliser circuits have been cut.

  7. Pingback: How effective is your Immobiliser? | Obsessive Vehicle Security Blog

  8. ALF says:

    When an installer puts in an aftermarket system with immobiliser, will they disarm permanently my factory one? I have a factory and got installed the AVS S5 with 3 more.

  9. Julian Julian says:

    If you have a vehicle with a transponder immobiliser then AVS (or who ever the installer was) have sold you something thing that you don’t need. Personally I’d take it back and ask for a refund.

    The factory system on most cars is far more sophisticated then anything AVS have to offer and I’d be very surprised if your installer could get past one. Out of interest have you actually asked your installer this question? If so what was the response?

    The Thatcham CAT 2-1 category is for cars that already have an existing immobiliser yet require an alarm.

    The following are suitable for cars with an existing immobiliser:

    OEM upgrade alarms work off the existing vehicles remote.

    Remote upgrade alarms come with remote controls for vehicles that require keyless entry.

  10. Sarah Dorton says:

    Hi Julian we have a Toyota Hiace for work which has an aftermarket fitted immobiliser with the tag which are on the key ring. One of them has stopped working, so they key on that ring will not start the car. Is it possible to get a new one of these tags? One is still working, they are about 1 inch in length and slightly rounded. If it is possible can you let me know how much it would cost please. Many thanks Sarah

  11. Julian Julian says:

    Hi Sarah,

    I’ll need to know some details such as your location and what make of transponder tag it is. Check the remote page to see if it is one of the tags I have a photo of and either let me know which one it is or send me a photo of what you have.

    Please fill in the Contact Form so I can get the details I need rather then publishing your details on the blog.


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