Dear Car Talk:

I have a 2012 Ford Fiesta five-speed. The check engine light is on, and the computers at AutoZone and Big O say it's the catalytic converter and oxygen sensors. This will cost me about $850 to fix. I'm pretty middle class. Since I'd rather buy lottery tickets with my money, can I just have a guy take out the catalytic converter and put in a straight pipe? We don't have emissions testing where I live, in Indiana.

Please tell me how dangerous it is to drive with a "bad" catalytic converter. Will it destroy my engine? Will fumes back up into my front seat and make me drive into opposing traffic? Thanks. -- Marlyce



A 2012 Ford Fiesta ... you lucky devil! Here's the good news, Marlyce: Driving with a plugged-up catalytic converter shouldn't permanently harm your car.

At some point, if the converter gets completely plugged up, it'll diminish your power. And eventually it'll prevent the car from running at all. It'd be like having a potato in your tailpipe. Then you'll have to remove the converter if you want the car to run again.

As long as the exhaust system is intact, without leaks, you won't get any fumes in the passenger compartment. Of course, the same can't be said for the poor jamokes who are driving behind you.

The bad news, Marlyce, is that it's illegal to remove your catalytic converter. Federal law sets baseline emissions requirements for all cars in the United States, and gasoline-powered cars can't meet those emissions requirements without catalytic converters.

States are welcome to set emissions limits that are more strict than federal law, but not less strict. So you would be a criminal, even in Indiana, Marlyce. On the plus side, stripes can be slimming!

Now, in reality, since Indiana does not require emissions testing, it's unclear to me how you would ever get caught. But you'd still have to wrestle with something known as your conscience.

So it's your choice. You could save $850 but increase the chances that you, your kids and your neighbors will get asthma, brain tumors and mutated DNA. Or you could spend the $850, sleep well at night, but wake up every morning and wish you had an extra $850.

Actually, you don't say how many miles are on your Fiesta. But emissions components -- including catalytic converters and oxygen sensors -- are all warranted for eight years or 80,000 miles. So if you've got 79,999 miles on the odometer, have it flat-bedded to the dealer and get that stuff replaced for free.

If you're out of warranty, I can't tell you what to do, Marlyce. But if I could, I'd tell you to be a good citizen and replace the converter.