Nissan Repair: Carbon Monoxide, computer diagnosis, carbon monoxide poisoning

Question
Had a new radiator and thermostat installed, next day I ended up in the hospital with carbon monoxide poisoning.  Dealer can not find a leak in exhaust and computer diagnosis is fine.  Has small oil leak from valve cover, that's all....Any ideas?

Answer
Melissa,

If there is a hole in the firewall or under the body and exhaust can get it you can get carbon monoxide in the cabin,  I would check the car for leak paths into the car.  Usually, on an older car the vents in the body, at the back, behind the bumper or tail lights can get stuck open and that can let exhaust in the cabin.