Author Topic: Catalytic converter blown?  (Read 1154 times)

ciciban

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  • My Honda: Honda Jazz Mk1, 2007, 1.4
Catalytic converter blown?
« on: March 22, 2022, 10:18:50 AM »
Hey guys,

I bought very clean looking Honda Jazz, 1.4 in blaze orange 2 weeks ago and I have a small problem with it. I can hear rattling noise coming from around the catalytic converter at idle and around 2000rpm. Before I bought the car, I brought it to local tech inspection place to check it and they said it's just loose heat shield. A few days ago I went to my mechanic to fill up AC and to check the rattling noise. He said that the cat is blown and needs to be replaced, turns out to be around 200€.

So I was wondering if this is a common issue on these Jazzes?
Thanks for help

culzean

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Re: Catalytic converter blown?
« Reply #1 on: March 22, 2022, 11:17:32 AM »
The CAT may have been stolen at some time and a cheap one fitted,  has a cage been fitted around the CAT, this may rattle, a loose heatshield may also rattle.  A CAT that has failed internally probably will not rattle but will affect performance and emissions.  No particular problem with the CAT on a Jazz except they are easy to steal.

https://mechanicbase.com/engine/bad-catalytic-converter-symptoms/
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

ciciban

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Re: Catalytic converter blown?
« Reply #2 on: March 22, 2022, 12:41:33 PM »
Thanks for your reply.

Cat is original, mechanic confirmed and the car has done 92000 miles so it's really soon for the cat to go (I think). My mechanic said the ceramics inside the cat has fallen apart and that's what's causing the rattle. I don't have any check engine lights, nor worse fuel economy, etc.

culzean

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Re: Catalytic converter blown?
« Reply #3 on: March 22, 2022, 01:08:57 PM »
Thanks for your reply.

Cat is original, mechanic confirmed and the car has done 92000 miles so it's really soon for the cat to go (I think). My mechanic said the ceramics inside the cat has fallen apart and that's what's causing the rattle. I don't have any check engine lights, nor worse fuel economy, etc.

Your car will tell you if CAT has collapsed internally,  remember there is a thriving market for Jazz CATs, so do you trust the mechanic to not fit a cheap new one and 'trade in' the valuable older one for scrap or to fit to another car ( older CATs have far more precious metals in them than new ones ).
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

embee

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Re: Catalytic converter blown?
« Reply #4 on: March 22, 2022, 06:46:59 PM »
I wouldn't immediately accept your mechanic's diagnosis. It's not common for the ceramic monolith to break up unless the casing has been bent or damaged. The monoliths are quite fragile out of the can, but they are mounted in matting which protects them from shock when fitted inside.
If you have serious engine faults, misfires etc, it's possible for the monolith to have thermal runaway and they can melt, but the engine management system will flag such faults and should usually protect the system by shutting off fuelling to non-working cylinders for example.
The ceramic isn't particularly hard and tends not to rattle, not such that in makes a noise you will hear anyway.
If it has broken up it would very probably give a fault warning (MIL). If it is driving normally then it hasn't blocked the gas flow.

My guess would be it's far more likely to be something metal, such as a heatshield as others have noted. Replacing a cat will provide more income that trying to fix a heatshield, not that I'm cynical at all.
Of course trying to diagnose at distance is difficult and it could be broken up.

richardfrost

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Re: Catalytic converter blown?
« Reply #5 on: March 23, 2022, 04:32:12 PM »
What IS common in the Mk.1 Jazz is the heat shield to come loose and rattle. A number of owners have mentioned this. Ours came loose and rattled, similar to how you are describing it, about 5 years ago. We removed the heat shield and did not replace it. The car has been fine without it.

Skyline84

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Re: Catalytic converter blown?
« Reply #6 on: March 23, 2022, 04:34:09 PM »
The catalytic converter on my 2004 Jazz has been rattling for well over a year. I asked my mechanic to look at it when the car was in for an MOT - he confirmed that the rattling was coming from within the catalytic converter itself, and it wasn't the heat shield (which is what I thought it was). I asked about a replacement, but as the car passed the emissions test with flying colours and drives absolutely fine, he advised to leave it for now. The rattling hasn't got any worse since then (and it has been through and passed another MOT in that time) so I'm not in a hurry to replace it. 

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