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Discussion Starter #1
Hi Guys,

Got the MIL on with a P0430 Catalyser 2 error (MultiECUscan). Also got notable smell of gas fumes (outside the car) when running hot. Almost didn’t pass the MOT due to elevated emission levels. Otherwise car in running fine.

So, - pretty sure one or more of the CATs are gone… question is which one..

Each head got a pre-CAT and a downstream CAT in the center dual exhaust CAT-assembly

How do you determine if it is the pre-cat or the center cat that is gone (if not both) …?

Any tips or experience with faulty CATs on a 3.2 159/Brera
 

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I’m sure that’s bank2
It’s got to be rare for one of these cats to go. It’s worth having the headers checked for leaks.


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Discussion Starter #3 (Edited)
Hi Guys,

Got the MIL on with a P0430 Catalyser 2 error (MultiECUscan). Also got notable smell of gas fumes (outside the car) when running hot. Almost didn’t pass the MOT due to elevated emission levels. Otherwise car in running fine.

So, - pretty sure one or more of the CATs are gone… question is which one..

Each head got a pre-CAT and a downstream CAT in the center dual exhaust CAT-assembly

How do you determine if it is the pre-cat or the center cat that is gone (if not both) …?

Any tips or experience with faulty CATs on a 3.2 159/Brera
Did some further investigations.. Below pic shows output voltage from all four O2 sensors pre- and after cat, Bank 1 and 2.
Pls. note that the pre-cat sensors are wideband sensors.

Looking at Bank2-after-cat sensor its oscillating like crazy. I believe it should look steadier like Bank1-after-cat.
As far as I know the oscillation is a clear indication that pretty much nothing is happening in the Bank2 cat i.e. it’s gone. Right…?

Now, each Bank has two cats. One built into the exhaust manifold and one downstream under the car (two for each bank - four in all) Any idea on how to determine which of the Bank2 Cat's is working/bad… would measuring operating temperature of the cat's tell me anything… or …?

935786
 

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Discussion Starter #4
I’m sure that’s bank2
It’s got to be rare for one of these cats to go. It’s worth having the headers checked for leaks.


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Hi "Clay19"

Thanks for the input.

I would say so too. It would be rare... however I have seen Cat's go on my 156 as well back in the day....
 

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I would be concentrating on the main cat rather than pre cat,not sure on these engines but on my old scooby you could ditch pre cat and emissions and o2 readings were still spot on.

as for your readings that suggests the cat is knackered as it’s oscillating like pre cat o2 should,after cat it should be fairly steady as gasses should be cleaned by time it reaches that sensor.
 

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Or the Bank 2 Post Cat O2 sensor could be FUBAR.

You can remove the Precat O2 Sensor and use a inspection camera to take a look at the cat and see what condition it is in. (Broken/disintegrating/missing) if it appears to be intact and in good condition I would change out the Post Cat sensor first before looking at the very expensive prospect of replacing the Cat.

Just a thought.
 

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Discussion Starter #7
An update on my cat converter issue.

Checked the left bank manifold with an inspection cam though the top O2 sensor. Looked OK – but couldn’t really tell for sure. Also did an IR temperature reading but didn’t have a reference to compare. So decided to take it out of the car.

Took a bit of work to get the thing out. Not too many issues apart from a couple of rusted bolts that needed some persuasion.

My suspicions turned out to be true and the root cause of the emissions error codes has been identified i.e. for now anyway. About 1/3 of the honeycomb catalytic materials seem to be missing.

Sourced a used Cat at a salvage yard in the Nederland’s for about 400 Euros.

Will drop it in and see how it goes.
 

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Have you checked the secondary cat under the car as well? If the manifold cat has dropped half of its internals, they could have found their way into the secondary cats.
 

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Discussion Starter #9
Have you checked the secondary cat under the car as well? If the manifold cat has dropped half of its internals, they could have found their way into the secondary cats.
No, not yet. But that was my thinking as well... where did all the bits go...(?). Will check on it later. However, the ceramic is rather porous so hopefully most has passed over time
 
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