THIS! ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^

How it all works:
The alarm siren sets itself off when its old and its batteries leak and ruin the circuit board.
OTHER THAN THAT, the CLP/SSM is what sets off your siren.

What is wrong:
The CLP/SSM is compromised due to water intrusion.
or...
The CLP/SSM microcontroller is damaged by electrical disturbances ("surges") due to running for years with a weak battery (I change my battery at 48 months, period).
or....
Once locked, one of the following is indicating intrusion: Console storage compartment door "closed" sensor, glove box door switch, one of the car's door switches, engine hood/lid switch or the trunk latch switch. Also, the two sensor can false and think the car is being towed. I am NOT so sure those codes you are getting are a clue; they are used to sense if a hose is leaking but I am not so sure that the alarm would be triggered on one - it is clear from the code descriptions (if we can trust them and much of our documentation is wrong/incomplete so who knows?) that the SSM knows it has a slow locking action, NOT that there is intrusion.