My cars have a remote start timer where the cars shuts down after a period of time. That would be a crazy crime... hide in the bushes for an hour or two continuously restarting the car every 10 minutes.
We have a 2019 Honda Pilot. The remote start will work for two 10-minute cycles, but then it will not work again until you start it via the primary ignition switch inside the vehicle. Other manufacturers may differ on this behavior however.
Step 0.5, break in and disable all the CO detectors.
This assumes the target's attached garage is part of the conditioned space making up the rest of the home (i.e. that there's no air sealing around the door between the house and garage, but the garage door itself is perfectly sealed). That would be a pretty spectacularly bad house design.
Old houses can be pretty leaky between the garage and living space. Or doors can be left open. But many vehicles’ remote starters have a timeout exactly for this specific safety concern. Between this and modern catalysts, remote starting a car in the same room as you isn’t even likely to kill you.