Cobra AK4138

The Cobra AK4138 is quite simply in a league of its own when it comes to the world of high-end remote alarm/immobilisers.

Basically, it’s the AK4198 and the 8509 combined. Together the system is a full-blown Thatcham Cat 1 system with plenty of cool options.

It is designed for older vehicles that do not have a factory transponder immobiliser and keyless entry.

Cobra AK4138 Modular Alarm System

The system is completely modular which means that the Siren, Alarm ECU, and immobiliser are all separate. They communicate with each other via a secure bus network.

There are a number of advantages in having separate modules. The first is that they are small and easier to install into tight areas. The second is that most alarms give away the immobiliser location by containing the indicator relays, these click when the alarm is triggered.

The bus network monitoring means that if the siren is unplugged, or the cable to the siren gets cut, not only will the siren sound, but the alarm will also be set off.

 If any items have been disconnected whilst the system is disarmed the alarm will report a fault. This way if you have a dodgy mechanic or some unscrupulous bastard tampers with the alarm you’ll know about it. The alarm will chirp to warn you that something is not right, then the LED will flash a fault code.

Superb Immobiliser

8509The AK4138 has 3 immobiliser cuts as standard.

The main alarm ECU immobilises the starter motor, and the modular immobiliser cuts two running circuits. If that is not enough an additional 8509 immobiliser module can be added for an additional two cuts.

The Cobra immobiliser is the only system in NZ that is totally attack-proof.

Digital Battery Back-up Siren

Cobra Siren

The 4310 Digital siren is simply in a league of its own as it is fully waterproof. It’s rugged too and the battery pack lasts for years. It makes most other sirens on the market look compromised.

If that is not enough then the AK4138 has a dedicated horn honk output, or a second 4310 siren can be added to the bus network which can be used as an internal screamer, or as a second external siren.

If you want to hear one in action then I have one installed on Obsessive Wagon.

Rugged remote control

The Remote controls are waterproof and Muppet proof with two simple buttons that do what they should.

The lock button will arm the alarm, and also has the option to activate the optional window closure. A second press will disable the ultrasonic sensors giving the user the option of leaving a window open, and a 3rd press will disable the optional microwave or tilt sensor (perfect if you want to take the car on a ferry). Once fully armed (after 22 seconds) the lock button will activate the car finder mode then a second press will act as a panic alarm.

As for the Unlock button, well it disarms the alarm and unlocks the doors! It will also disarm the immobiliser once it has auto armed.

Ultrasonic Movement Sensors

Cobra Ultrasonics look factory fitted

Cobra Ultrasonic Sensors look factory-fitted

Ultrasonic Sensors come as standard. These are far more effective than the glass break sensors found on most other alarms.

They look the part too and can be painted to match the trim of your car if need be. I find that the grey colour matches about 90% of cars, but for those that are not grey, I normally have some pods which I have pre-sprayed black just in case.

Cobra AK4138

RRP: $850.00
Insurance Approved: Thatcham Cat 1
Obsessive Rating: 10/10
Looking at some of the alarms that claim to have a 5-star rating to it would only be right to give the AK4138 a 10 Star rating. It simply is that much better than the competition!



Additional Information:

Siren power: > 115 dB (A)
Max. consumption: < 19 mA

PDF icon4100 Series User Manual

Foot Note:

Common Question: Is the AK4138 is still the best remote alarm/immobiliser available due to it being a number of years old now.

The answer is a yes.

Why is it still the best after all these years?

Well its made for older vehicles that do not come with a factory transponder immobilizer or existing keyless entry, therefore it does not need software updates or the ability to tap into the vehicles CAN-BUS. If you have a modern car with these features then take a look at the AK4615.

It’s simply the best option if you have a high-risk vehicle that lacks modern security features.

Julian 01/07/2016

This entry was posted in Car Alarms, Cobra, Reviews, Vodafone Automotive and tagged , . Bookmark the permalink.

22 Responses to Cobra AK4138

  1. Laura says:

    Hi, do you know any any guys around the Auckand area that supply and install these for a good price?

  2. Julian says:

    Hi Laura,

    Wellington is only an 8 hour drive from Auckland and you wouldn’t be the first to travel that far for a decent install 🙂

    I’ve sent you an email with your options for up that way.

  3. Marco says:

    Hi Julian.

    Any Cobra AK4138 options for us down here in Christchurch? 🙂


  4. Julian says:

    Hi Marco,

    Not that I’m aware of, however I’m a big fan of the Interislander and Bluebrigde ferries, and Wellington is a seriously great city to visit and to have a night out in. (You wouldn’t be the first!)

    If I get enough interest I may consider a working holiday down to the Mainland 🙂

  5. Pingback: Obsessive Road Trip 2012 | Obsessive Vehicle Security Blog

  6. kendall says:

    Hey there am wanting this alarm I live in nelson where can I get it from?

  7. Julian says:

    Hi Kendall,

    There is no Cobra dealer in Nelson, I’m toying with the idea of doing a working tour of the South Island so if you’re keen then let me know.

  8. James says:

    Hi Julian,

    First of all, thanks for providing the information regarding the car alarm. Have learnt a lot from your website.

    I am just wondering if you could recommend car alarm installer in Auckland. My friend gave me 2 Cobra alarms and I am looking for someone to install it. Really sorry that Wellington is just a bit too far. Wellington is indeed a great city and I have visited it a few times. Thanks

  9. Julian says:

    Hi James,

    I don’t know of anyone in Auckland that I could confidently recommend as most decent installers will only install systems that they are supplying. Have a read of this post which explains why:

  10. Pingback: Cobra AB7928 | Obsessive Vehicle Security Blog

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  12. Pingback: Subaru Impreza such an easy target! | Obsessive Vehicle Security Blog

  13. Rob says:

    Hi Julian

    Thanks for an informative website!

    My trusty Surf was stolen a few days ago and I’m still in the standown period before insurance pays out. Whether I get it back or end up buying a replacement Surf, I will be wanting a serious alarm/immobilser option.

    One of the Cobras seem the favourite option. I’m based in Auck and would obviously prefer a local expert installation but if you aren’t active in Auck then I would consider the drive to W’ton and make a long weekend of it.

    Which model Cobra would you recommend for a late 90s or early 2000s Hilux surf? and what would be the approximate cost inc installation?

    Since losing my Surf, I’m now paranoid about car security and wondering whether the standard factory immobiliser on my 2002 BWM 330ci is adequate or not – any thoughts?


  14. Julian says:

    Hi Rob,

    Sorry to hear about your Surf, it seems that a large number of 4WD’s are getting targeted right now.

    I only cover Wellington. The AK4138 would be what I’d recommend. I suggest flicking me an email ( to go into any details rather then discussing in public here.

    Most factory immobilisers are effective however I am aware of this:

    If it’s happening here in NZ I have no idea!

  15. Ali says:

    factory alarms and immobilizers are easy to bypass provided you have the right knowledge and equipment, for some car manufacturers its easy as cutting one wire or grounding one wire to bypass the factory alarm, thieves these days have so much information from the net, vehicle wiring diagram, mates who work at car dealers that keep a cloned copy of the key ones the car is sold, i have seen some serious master mind jobs of car getting stolen, believe me i have being installing alarms for 5 years now and some cars that have a high price tag have a low security system.

    Going with a professional installed alarm is the only way. sometimes i will pull the whole chunk of dash board out just to hide a uniden/ moongose alarm brains because the modules are so huge.

  16. Tim says:

    Hi, I’ve found your website so helpful in working out what alarm I want for my car. I have a Subaru Impreza ’97, that doesn’t appear to have any standard immobilises they’re producing now. Would this be a problem with installing or functioning of the Cobra AK4138 OR AB7928 models as I see these both are CAT 1. With this model of car, and well known poor history of break ins – so far so good, and want to keep it that way, what alarm would you recommend to protect it well? I’ve looked into the 446RLI premium that sounds good as well.

    I look forward to your advice!



  17. Julian says:

    Hi Tim,

    All systems would work fine with your Impreza, however I suggest that you flick me an email to nut out the details, rather then chatting about your cars security on a public forum.

    Either fill out the contact page:
    or send me an email with your details including your location.


  18. Jim Bell says:

    I have a Vauxhall Vivaro 2013 Sportive.
    The van was bought at auction and I only have one key.
    How much would it be to install the alarm discussed above to renew the entire system.
    Also I’m based in Chch so would need to book in and spend the day.


  19. Julian says:

    Hi Jim,

    Your Vivaro should already have a factory transponder immobiliser so the Cobra AK4198 would be my recommendation if you are after a remote alarm. I’d also recommend getting a second transponder key as if you lose your only one it’ll cost a small fortune to get the van running again.

    Does your existing key have lock buttons? If so the Cobra AK4615 could be an option.

    Feel welcome to email the details rather then posting everything here in public.


  20. Paul Kitchenman says:

    Hiya Julian
    Can you recommend anyone in Auckland …Great website and you are the man for the job…sadly can’t give you the business..being Im in Auckland ..Regards Paul Kitchenman

  21. Julian says:

    Hi Paul,

    I’m planning an Auckland road trip soon so could do the install up there for you.
    Flick me an email with your car details to

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