S Type security back up sounder and immobiliser

[plaviator]

I know that there is an old post about this but I have a similar problem. The difference in my case is that the main car battery is new and fully charged and also not only does this alarm sound but it actually does immobilise the car. the car is a 2005 S type 2.7D

So the situation is this: one hot day I heard the beeping noise from under the bonnet of the car. This was not the horn but a high pitched beeping which I had never heard before. Even though I unlocked the car with the fob, it still continued to beep and when I tried to start the engine, although it turned over, it would not start. I then disconnected the main battery and the alarm stopped. After 10 minutes I reconnected the battery but although the alarm did not sound, the engine still would not start.

I then connected my iCarsoft diagnostics and it came up with 7 faults on the engine, including crankshaft position sensor, MAF sensors, Turbo boost solenoid, No 6 cylinder injector and others. This was without the engine running and had previously run perfectly. I then cleared all faults and the engine started normally. When I then ran the diagnostics there were no DTC faults.

Now, if I leave the car locked overnight, the immobiliser has always activated in the morning. Whether the alarm sounded I don't know as I can't hear it from my bedroom. If I leave the car unlocked then it is fine in the morning.

Can anyone advise me as it appears that I cannot access the immobiliser with the iCarsoft LR V3.0