What do I need to do? I don't remember seeing carbon monoxide detector on the student required items for purchase list.....
To Newfound, and others interested, yes, there are many CO detectors available, from the one time dot which changes colour, to the various electronic versions. I advise that you stop by your local fire station, and ask for a little education. If the firefighters have time, they would probably be happy to help. Ask to see a "bump test" which is the calibration of an electronic CO detector with a precision gas. I have a digital CO detector, which I use for CO testing of modified aircraft, and use on my plane a few times a year, and at the time of annual inspection.
The cracks in a muffler which can cause a CO leak into the heating system can be very small, and hard to detect. There are numerous Airworthiness Directives to check for this defect, but it's not full proof. If you're flying a non pressurized plane in a temperate climate, turning off cabin heat, and opening cabin air is a great way to reduce possible CO. If you have the air vent blowing at your face, it is unlikely that CO poisoning will be a risk.
Turbine airplanes can use bleed air for cabin heat, which assures no CO. But aircooled piston powered planes have little choice than to use some form of combustion to produce heat. Combustion = CO, no matter what. A muffler heat exchanger which is well maintained is a good system, but defects are common, and maintenance to find them involved. If I were a renter, I would buy a few of the black dot type CO detectors, and assure that one is near my pilot position during flight in a rental. If I were a club, I would have one digital CO detector, and ask pilots to take it randomly in club airplanes, and note the results. CO is a real hazard, and if it's going to get you, you will not know as it is happening to you, unless you have a detector.
And, let's keep the posts polite and on topic please....