How long should a catalytic converter last?

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If the engine is in good shape mechanically the cat should last the life of the car. There are a few exceptions.....Cars with known problems.

Seems on every automotive board I visit people don't change plugs or wires untill they are completly worn out and causing a misfire or misfire code.

But it was misfiring ocasionally long before the code poped up and IMO this kills Cats too.

When we sell a Cat. Inside the box is a piece of paper that says to fix the problem and not the symptom.
 
Oil burning or excess fuel will puke a cat early.
And all cats do not have the same design or materials - some are undersized.
I have found Hondas to have deposits in the cat more than others.
Some of this was the common oil burning in the otherwise good engines.

As to letting the fuel get way low, the problem is not lean, but rich!
As the engine misfire, is sends raw fuel to the cat. This is a rather rare problem. And, you'd know when the car is misfiring.

Cats nowadays last longer. The science is better, and FI gets more and more precise. Oil burning is not as common at all as it once was.
 
My 17+ years old 1994 LS400 at more than 260k miles still has all original pipes, mufflers and catalytic converters. The only parts of the exhaust system had been replaced 2-3 years ago was 2 pre-cat O2 sensors. Probably under the car parts can lasted that long because we have no salt on the roads here during winter months and very little rain too.
 
The catalytic converter went on my 1988 Mercury Grand Marquis LS after only 90K miles, when I owned it.

From what I was told.... since I had bought the car new, a lot of stop and go traffic in NYC, along with the possibility of poor gasoline from brand name stations, and some quick lube oil change shops might have caused it to fail.

The only way I knew it needed to be replaced was when I accelerated with the car. Then the sound of stones and gravel like material would be bouncing around in the exhaust system. At first I thought it was the muffler.....but when I had someone look at it they confirmed it was the catalytic converter.

I do remember that it was an expensive replacement.
 
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Explain what do yo mean by catalytic converter gone? Is there P0420 code? Are your tail-pipe emissions beyond the limit? Is it leaking / rattling / cracked etc?

I will tell you that tripping P0420 is done when the converter efficiency drops from 99% to 95% (or something really like that). Very rarely P0420 code indicates bad tail pipe emissions.

My experience with three different cars from three different makers living in New England:- Between 60K - 140K and all four (one car had two) gave the dreaded code. All are immaculately maintained.

- Vikas
 
Had to say exactly why a cat has failed. Both my rear ones (it has four cats) have been replaced. One went with 28k and the other with about 32k. In that case it was some sort of manufacturing defect. A TSB was out on the issue.

Running rich is commonly cited as reason for failure, but running lean will cause it to overheat as well.
 
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Originally Posted By: mopar_monkey
is the cat efficiency below acceptable range or is it cracked? these year civics tend to crack the cats causing exhaust leaks.


I am not entirely sure why the mechanic told her it needed replacing, it's entirely possible he's a shady mechanic trying to make a buck!
 
Originally Posted By: Bill in Utah
Originally Posted By: RI_RS4
By law the catalytic converter has a warranty of 8 years or 80,000 miles.


Patman is in Canada. I'm sure their LAW is different?


Actually I believe it's the same up here. Since it's my ex's car, I don't have the owner's manual handy, but I know on my Corvette the emissions warranty was 8 years or 130,000 km (which is 80,000 miles)
 
Originally Posted By: Artem
Unless you have yearly inspections, why worry about replacing it?


In order to get our plate sticker, we need to have an emission test done every 2 years up here (on cars older than 7 years old) and it just so happens that this car needs it's emission test in the next few months.
 
Originally Posted By: mechtech2
Oil burning or excess fuel will puke a cat early.



Bingo, this must be it! For the past few years this car has burned a lot of oil, when we were together it used at least a quart every 2500 miles (and I think it's burning even more oil now since we split)
 
My Saturn burned a quart of oil every 300-700 (gradually getting worse) during the time we owned it (for about 90,000 miles). The cat never complained or threw a code, finally got rid of it at 210,000something miles. I'm sure it wasn't good for it, though.

A quart every 2,500 miles isn't too bad, really. That's ~about what our Malibu uses.

The only converter I've ever had to replace was on a 205k mile Turbo Shadow. It had a random mis-fire at idle that I never did fix; I imagine that's what killed the first cat. There were pieces of it in the muffler - it sounded like popcorn when it would miss.
 
Originally Posted By: Virtuoso


A quart every 2,500 miles isn't too bad, really. That's ~about what our Malibu uses.



It's bad for someone like my ex wife who has no idea how to check the oil though. That means in 5000 miles her engine is running with less than 2 quarts of oil in the sump. And I think it probably burns about a quart every 2000 right now and will only continue getting worse. So if she goes 6000 miles between changes (which she probably will), at that point it will be running on only one quart of oil. I was topping up her oil for her for the first few months after we split up, but now I'm backing away completely and not getting involved with helping her take care of that car anymore.
 
The only car I have ever had to replace a cat on was my '91 Escort GT (Mazda 1.8), and it went through 4 in the 200K I had it (I bought it new). It ran like a top, and was used way beyond it's rated ability (towed trailers, track days, etc). They always failed during the same time of year, I ended up attributing it to water getting splashed onto it from puddles.

Each time the material would break apart before replacement.
 
That sounds a bit fishy to me, they failed about every 50k? Really?

Maybe someone was damaging the replacements so they would fail early too?
 
Yeah, I don't think anyone was tampering with them. I suspect, as I mentioned in the post above, that it was water being splashed onto them that killed them. I spent two of the years in Lakeland and two of the years in Tampa - lots of water everywhere.

It may have been towing the dirt bike trailer through the woods, or the flatbed trailer with 3 sportbikes all over the state for races. Or it could have been a design flaw.

The original clutch was still in it at 200K
 
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