Hi, I am new here , and was trying to figure out how to create a post , when i saw yours. My Mk3 Sport has the same issue . ie goes off, and despite starting the car , continues to go off. I have removed the sounder from the boot and was going to order another from ebay, but logic indicates it is the control unit that is sending it a false signal. I may try your approach as you can pick up second hand sounders easily. I did have a couple of questions though. a) Do you know where the alarm controller is located. I cannot find anything that tells me ( for obvious reasons i guess). I have ordered a replacement on ebay just in case it is that . b) do you need to pair the controller with the keys, or is the pairing done with a separate sensor. all help well received.
Hi. As far as I can recall, the control module is behind the boot trim as well, albeit in a different location to the sounder. As regards what needs to be done if the module is replaced, I can’t answer that as replacing the sounder cured the problem so I didn’t take it any further. I would suggest just replacing the sounder and only consider the module if that doesn’t cure it, as it’ll no doubt be much more complicated. I was just relieved to have a fairly simple solution in the sounder replacement.
Thanks - i will give it a try before plan B
Before you go replacing anything, thoroughly check out your bonnet microswitch. There are several posts describing this as the cause of random alarm triggering on the Mk3 and I found mine was just on the edge of triggering too, cured by judicious deformation (bit of bending) of the actuator lever.
There’s also the old chestnut of leaving a mobile phone in the central locker which will do it as well.
Thanks - Yes , had the Wifi problem with a another car a few years back - my radio door bell activated it! I did look at the catch and appears ok . As the alarm does not deactivate when i start the engine i am guessing it is something more down stream. I have ordered a new alarm sounder from ebay for £20 - so will see how that goes. Thanks again