My car stinks and I can't blame it on other cars forever.

November 17, 2009 9:42 AM

Should I bother fixing my catalytic converter?

Worth it to fix my catalytic converter? It periodically smells like rotten eggs and the mpg is down from 16 to 13 or 14 on the highway. '97 Mountaineer, but I don't use it to commute so it accrues 2500 mi/yr, tops. The car's only about 100K miles old.

Don't know how much this costs to fix. Would it just be cheaper to leave it alone? The car passed the Seattle emissions test by default a month ago, since it's too old to plug into the computer. But am I going to be sorry if I don't fix it when the car ... explodes or something?

posted by zvs to travel & transportation (10 comments total)

Speaking as someone who potentially could be driving behind you, I'd implore you to fix any and all emissions issues on your car.
posted by Burhanistan at 9:55 AM on November 17, 2009

It doesn't represent a safety issue, but a lot of states require that a car pass a pollution check in order for their license plates to be renewed. If you live in one of them, you won't pass the test without your catalytic converter working.
posted by Chocolate Pickle at 9:59 AM on November 17, 2009

As per my husband:

While it's annoying to have your car smell like sulphur, it's really just a symptom. The underlying problem is that the car is running too rich (too much fuel, not enough air) a mixture, possibly because of your injector ports. That's what's really reducing your gas mileage (not burning all your fuel) and causing the smell (when cats overheat, they stink, and too rich of a fuel mixture causes everything in contact to run hotter than normal).
posted by bookdragoness at 10:02 AM on November 17, 2009 [1 favorite]

The car passed the Seattle emissions test by default a month ago, since it's too old to plug into the computer.

Will it have to undergo a pollution test in which they insert sensors into the tailpipe to measure emissions? If so, it won't pass that test, and to keep it on the road you'll need to do the repair.

On another, perhaps more important point, cars with broken catalytic converters can emit literally hundreds of times the pollution they otherwise would. A lot of what you hear about the environment and cars has to do with carbon dioxide, but the emissions that actually affect the air you breathe are the ones controlled by the catalytic converter. With it broken, you're contributing massively to local smog, which is really bad for everyone's health. Please do your part for your community's environment and get it fixed.
posted by Dasein at 10:04 AM on November 17, 2009 [1 favorite]

(when cats overheat, they stink, and too rich of a fuel mixture causes everything in contact to run hotter than normal)

This is validated by my experience as well.
posted by Chrishartley at 10:05 AM on November 17, 2009 [2 favorites]

Sorry, pushed post too early. He says that if the cat smells like sulphur, it's probably bad too. A repair will probably run you approximately $180 for the cat and $50 per bad injector. Unless you're very familiar with doing your own car repairs/maintenance/tinkering-for-fun (or want a car project, since it's not your commuter), take it to a reputable shop.
posted by bookdragoness at 10:06 AM on November 17, 2009

Sorry, pushed post too early. He says that if the cat smells like sulphur, it's probably bad too.

I agree entirely.
posted by jefficator at 10:57 AM on November 17, 2009

...'97 Mountaineer...
...The car passed the Seattle emissions test by default a month ago, since it's too old to plug into the computer.

That's strange...I thought all passenger vehicles sold after 1/1/96 were required to have an OBD-II interface.
posted by jaimev at 12:01 PM on November 17, 2009

Thanks, all. Not what I wanted to hear, but what can you do.

jaimev: That is strange. I think you must be right, but the emissions testers definitely didn't plug in. (I'll have to look for the connecter when I get home.)
posted by zvs at 12:12 PM on November 17, 2009

An overheated converter will likely eventually disintegrate internally or clog at some point in the future. Either it'll make an unbearably loud noise or your MPG and performance will take a nose-dive.
You're going to wind up fixing it eventually so do it now before it gets worse.
posted by Jon-o at 5:08 PM on November 17, 2009