[BigGroter]

pawn Code:

public OnVehicleSirenStateChange(playerid, vehicleid, newstate)
{
    new siren = GetVehicleParamsSirenState(vehicleid);
    if (GetVehicleModel(vehicleid) != 415 || GetVehicleModel(vehicleid) != 560 || GetVehicleModel(vehicleid) != 541 || GetVehicleModel(vehicleid) != 426)
    {
        if(siren == 1)
        {
            static
            Float:fSize[3],
            Float:fSeat[3];

            GetVehicleModelInfo(GetVehicleModel(vehicleid), VEHICLE_MODEL_INFO_SIZE, fSize[0], fSize[1], fSize[2]); // need height (z)
            GetVehicleModelInfo(GetVehicleModel(vehicleid), VEHICLE_MODEL_INFO_FRONTSEAT, fSeat[0], fSeat[1], fSeat[2]); // need pos (x, y)

            CoreVehicles[vehicleid][vehSirenOn] = 1;
            CoreVehicles[vehicleid][vehSirenObject] = CreateDynamicObject(18646, 0.0, 0.0, 1000.0, 0.0, 0.0, 0.0);

            AttachDynamicObjectToVehicle(CoreVehicles[vehicleid][vehSirenObject], vehicleid, -fSeat[0], fSeat[1], fSize[2] / 2.0, 0.0, 0.0, 0.0);
            InfoBoxForPlayer(playerid, "~w~Siren lights: ~g~ ON");
        }
    }
    else
    {
        CoreVehicles[vehicleid][vehSirenOn] = 0;
        DestroyDynamicObject(CoreVehicles[vehicleid][vehSirenObject]);
        InfoBoxForPlayer(playerid, "~w~Siren lights: ~r~ OFF");
    }
    return 1;
}

Try changing it to that?