Even If CO Danger is Low, It's Not Worth The Risk

Dear Car Talk:

I have a 2020 Honda Pilot. I will occasionally use the remote starter to warm up the car in my garage, with the garage door wide open. I'll let it run for 10 minutes maximum.

The question is, is there a risk of carbon monoxide poisoning or any health concern when doing this?

Thanks. -- Craig

Not for me.

If the garage is detached from the house, the risk to your health is fairly low, Craig.

Oh, wait a minute. Our lawyer, J. Cheever Loophole, just called in on the red phone. He says under no circumstances can I approve of this. So, the answer is don't do it, Craig.

But here's a more nuanced answer, just so you understand where I'm coming from. Cars today produce far less carbon monoxide (CO) than cars of yesteryear. Between computerized engine management, fuel injection and catalytic converters, today's cars produce something like 95% less CO than cars did 50 years ago. But there still is carbon monoxide in vehicle exhaust. And since CO is lethal, it's best to be really careful around it.

Theoretically, if the garage is detached from your house and the garage door is wide open, the risk to your health -- when you arrive to drive the car away -- is low. With the car's tailpipe close to the wide-open door, you're unlikely to build up a concentration of CO high enough to do yourself in.

But if the garage is part of your house, you're taking a much greater risk. It's possible that your house's heating and ventilation system could allow fumes into the living areas. Or that the door between the house and garage isn't perfectly sealed.

And that's if your car is operating perfectly. What if it's not? If your catalytic converter is worn out, if the fuel mixture is off, or if you develop a hole in your exhaust system upstream from the converter, you could be producing a lot more CO than you think and not realize it.

So even though the risk is not as high as it was years ago, the downside is so serious that I'd pull the car outside to warm it up.

When it’s time to say goodbye to your old car, here’s the perfect solution: Donate it to your favorite NPR station. They’ll even pick it up at your convenience. Here's how.