What year and what engine capacity is your volvo? Try putting in as much information as possible when asking a question, in that way you will get answers pretty soon.
If this is happening there is a reason, one of the theft sensing parts is defective, perhaps a door switch. The system is computer controlled and can be scanned to ID any faults present, I suggest you do that diagnostic and then work from the fault received in the testing. The testing requires a special scan tool
run the fault codes
dark smoke ( black) is an indication of incorrect air/fuel mixture
this can be from leaking injectors, faulty seal , over pressure in fuel system, faulty heated oxygen sensors, blocked air filter, faulty MAF/VAF sensors
the fault codes reading will give a better indication of where to start in the fixing process
