I need someone to tell me where the carbon monoxide problem is coming from

Hey folks, got an air monitor telling me my C02 levels are way too high. Seems to rise with the heat, or air handler activity. So I already know the problem and when it happens, I just don't know why.

Every search result for "CO2 inspection" just comes up with services that sound like they will tell me what I already know. But I need someone to solve what the issue actually is, and either fix it or point me to who can.

Who does that in Miami? I'm in Surfside, specifically.