How long should a catalytic converter last?

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Patman

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I'm curious as to how long most catalytic converters last? I've never had one fail on any car I've ever owned, but my ex wife's 2000 Civic needs a new one and it's got only 122k on it. That seems kinda early for replacement to me. What would cause a converter to fail so early? I always kept up the maintenance on that car, and we've always run fuel from the major gas stations here (usually Shell or Esso)
 
I'd never had one that had to be replaced on my personal vehicles (so up to 400,000 miles and still working) but have seen quite a few needing to be replaced at my ex-work.

Seems that idling is not good as the Crown-Vics seem to be the top replacement candidate that I've seen.

122k is too early for my book. My Corolla has almost twice that and still good. Dad's ex-2001 Civic has around 170k and its still on the original.

Bill
 
Originally Posted By: Patman
What would cause a converter to fail so early?


The number one cause would be a misfire - causing the engine to run rich - which can overheat the converter.
The second most common cause would be using a fuel additive measured in the wrong proportions.
 
is the cat efficiency below acceptable range or is it cracked? these year civics tend to crack the cats causing exhaust leaks.
 
The most common thing is ZDDP, either from normal volatilizing or from oil burning. Other than that silicon from poor air filtering would be an extremely distant #2 and I have heard some fuel additives can foul the catalyst.

I've heard around 100k as a catalyst related failure point for vehicles using SJ/SL oil for most of their lives.

Edit: I just gave reasons for the catalyst no longer functioning, the reasons for actual failure are different and generally related to ignition (or rather failure of ignition). Also 100k is early for an actual failure, the information I heard was 100k for the point at which it needs to be replaced to pass emissions.
 
I don't think there is an answer. My first BMW had 250K on it when I sold it, my second BMW had 194K. Both had the original cats.

I had a Rabbit GTI back in the day that had the cat replaced at about 120K.
 
I believe also running a fuel tank very low.It would also suck in some air along with the mixture,then having the O2 sensor read as lean,then it adjusts richer,etc,etc.I read that somewhere.
 
Originally Posted By: daves66nova
I believe also running a fuel tank very low.It would also suck in some air along with the mixture,then having the O2 sensor read as lean,then it adjusts richer,etc,etc.I read that somewhere.


Boy if that is true then I'm in trouble!

I run my Corolla to the light EVERY tank and its got 215k with nothing ever wrong. In fact I've done that for decades (well to 1/8th of a tank when there was no idiot lights for gas) and never an issue on cat equipped vehicles.



Bill
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Originally Posted By: Merkava_4
Originally Posted By: Patman
What would cause a converter to fail so early?


The number one cause would be a misfire - causing the engine to run rich - which can overheat the converter.
The second most common cause would be using a fuel additive measured in the wrong proportions.

Second this. Misfire causes the converter to overheat, making a mess of the internals. At least there is a glut of converters on the market for that. Check a ricer board for a lightly used one. Most of those guys take them off and put a straight through fake converter in.
 
Last edited:
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?
 
My catalytic converter had to be replaced this year at 78,000 miles. It is a 2000 Mazda. The spark plugs and wires were replaced last year as a result of letting someone detail my car and he got water in the spark plugs. I use a synthetic oil and wix filters. I change the oil every 5,000 miles. When I use any additive I am careful about the measurements. I try to always fill the tank when it is between 1/3 and 1/4 tank. I do not understand why it happened but I guess some cars are more prone to failure than others.
 
I think also Helen that when ANYONE is making thousands and thousands of anything that you may have got one of those "made on Friday/Monday" cats that failed.

We probably could have taken another CAT or Mazda and its just fine at twice the mileage.

Just got "lucky". MY Uncle has a 2005 F150 and has had to replace pretty well everything dealing with the power window in his left door this last month. Sad for a 5 year old vehicle. But I'd bet there are many F150 that have more window cycles with no issues.

Just the luck of the draw... Like my Dad says;

"You pay your money and take your chances"
 
Originally Posted By: Warstud
How do you know it needs replacing?


Good question. On my 2004 GMC it came up with a "bad cat" code and it ended up being only the post o2 sensor that I replaced.

Bill
 
They should last as long as the emissions warranty covers them. That pretty much is the basic answer.

I've only ever had to replace one. This was on my '88 Cherokee, and it failed due to the engine running rich for an extended period of time. My wife failed to mention the engine running colder than normal for an entire winter (thermostat was stuck open), and it smoked the cat. It was about 22 years old and had about 115,000 on it when it failed. You could tell because it rattled like crazy due to the catalyst falling apart.

I'm also with Bill on this one - sometimes there are just those cases that the statistics finally catch up - 99.9% reliability rate still means that 0.1 are going to have a problem!
 
Originally Posted By: daves66nova
I believe also running a fuel tank very low.It would also suck in some air along with the mixture,then having the O2 sensor read as lean,then it adjusts richer,etc,etc.I read that somewhere.


The engine would be stumbling at this point, and most people would then be looking for a tow in very short order.

Wife had the cat replaced on her '01 Civic due to a crack in the manifold--integral cat in the manifold. Expensive item.

I've heard that Toyota cats seem to die early. And that using non-OEM ones won't clear the code; or that they last an even shorter time. I do know that they tend to stink more; maybe they are less tolerant of lousy gas?
 
Unless you have yearly inspections, why worry about replacing it?

My 98 Camry V6 has 210,000 miles on it now, i've had a CEL (check engine light) for "low threshold" in the CAT for the past few years and a good 60k miles if not more. Car still runs good and returns awesome gas mileage. I'm in FL so i don't have to worry about emissions, period, so i just keep running it as is.
 
Depends on what was done to the car, I mean in the Trans Am I run a nice rich tune for the N20. The cats, won't last too long. Something like the Honda, assuuming it was maintained properly could go the life of the car. Who knows maybe the exhaust got bumped hard enough once to cause internal damage to the Cat. I have seen that before. It is possible the cat was just not that good from the get go. I have only had to replace one on any of my rides, and that was my old 89 GMC 1 ton. Miles of heavy towing finally melted what was a less than a stellar cat to begin with.
 
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