Recent inquiries here and at my shop have led me to create this thread in hopes of enlightening vehicle users about what cat converters are, how they can be damaged, how they can damage an engine, and how they can be fixed.

If you look at the diagram attached (It's from a lexus Rx 300 exhaust) items 17400 and 17410 are the pre-cat converters which we'll concern ourselves with today.

US vehicles are mandated to have catalyst to minimise emission pollution from car engines. For a lame man, it means a foamy/netty substance is put into those 2 exhaust pots to regulate exhaust fumes coming from the engine.

Now each of the cats has an oxygen sensor above and one below. The one above is the air/fuel ratio sensor which majorly regulates fuel delivery and the one below monitors the efficiency of the foamy/netty substance inside the exhaust pot.

Over time, that foamy/netty substance either gets clogged or breaks up in pieces. This results in different issues
When clogged, the following occurs
Engine hesitation (for example the car will struggle to climb a hilly road)
Engine pinging on acceleration
Bad fuel economy because the engine has to work harder to move the car since the exhaust cannot breathe
Engine overheating

When it breaks up into pieces, the following occurs
Engine eats oil
Engine damage(complete)

I will be back in a few hours to continue.

Continued:

When your vehicle has a catalyst issue, there are 2 alternative fixes

1. Replace the catalyst with a brand new unit(Note I said brand new unit. If you attempt a tokunbo replacement, you'll either get one which has been filled with the "ladipo" element in the exhaust pot or you'll get one fresh off a used vehicle which may have also failed as well)

2. Hollow out the exhaust pots and rid them completely of the foamy/netty substance inside them. Now because your car's computer has been programmed to accept a certain level of exhaust fumes to be detected by the monitoring o2 sensor, the consequent rush of exhaust fumes which it will detect in the absence of the foamy/netty substance will signal a red flag and you will get catalyst codes. Therefore to complete the fix, you must install an oxygen sensor spacer to limit the fumes seen by the monitoring o2 sensor. See attached. The spacer is screwed into the oxygen sensor before finally being screwed into the exhaust.

Whichever route you take out of the 2 options, a "self-learn reset" (google it) must be carried out to get maximum benefits from the repair.

Cheers

.....

Bros I need this spacer, how do I get it. I'm in ph. Rgds

thank u very much for this trend.i use a 1999 Honda Accord.the problem started with exessive fuel consumption to engine over heat.finally,thick smoke started coming out of the exhuast.my mechanic now advised me to change the engine.i just did that a few weeks ago.right now the engine is overheating when i put on the air conditional when the sun is very high.plz advice if its the catalyst thing that is the problem.i need ur advice.
you can reach me on ichehoke@yahoo.co.uk.....08074117062 BB PIN 21207e9d

Ateke, I have responded to your text.

Leke, I cannot confirm your issue without checking the car out physically.

Be informed!

i inspected my bmw and i discovered that it had been opened but welded,i.e,the pot. I've been wondering what happened 2it. It doesn't consume fuel but it sounds kindof buzzy but still fast like its stock. Someone told me the 'muffler' i.e, cat con. isn't there, pls could that be the cause of the buzz? If it isnt there then why isnt it consuming fuel (maybe my judgement is wrong), though i enjoy the noise, sounds like a turbo engine.
My question is, how do i know it's there or not?

If you have that deep drone sound in the exhaust then it's been removed.
As said previously, you get better fuel economy with it removed contrary to what local mechanics will tell you.

nissparts: Continued:

When your vehicle has a catalyst issue, there are 2 alternative fixes

1. Replace the catalyst with a brand new unit(Note I said brand new unit. If you attempt a tokunbo replacement, you'll either get one which has been filled with the "ladipo" element in the exhaust pot or you'll get one fresh off a used vehicle which may have also failed as well)

2. Hollow out the exhaust pots and rid them completely of the foamy/netty substance inside them. Now because your car's computer has been programmed to accept a certain level of exhaust fumes to be detected by the monitoring o2 sensor, the consequent rush of exhaust fumes which it will detect in the absence of the foamy/netty substance will signal a red flag and you will get catalyst codes. Therefore to complete the fix, you must install an oxygen sensor spacer to limit the fumes seen by the monitoring o2 sensor. See attached. The spacer is screwed into the oxygen sensor before finally being screwed into the exhaust.

Whichever route you take out of the 2 options, a "self-learn reset" (google it) must be carried out to get maximum benefits from the repair.

Cheers

Where does one get a brand new catalytic converter in Abuja. I have a check engine light on my 2004 EOD V6. i went for scan and the code P0470, P0471 AND P0430. The culprits were the O2 sensor at bank 1 and bank 2 and also the catalytic converter in bank 2. i changed the two O2 sensors only bt the CEL came up again. i went for scan bt only the code P0430 came up ie catalytic converter in bank 2. The car still guzzle fuel when compared to others that uses similar car with me. i think the problem is the catalytic converter. Now the issue is, where do i get a brand new one in abuja because i do not want to get a used one as i may not know the state of it. Also, are u saying that, using oxygen sensor spacers can solve the issue of bad O2 sensors or catalytic converter. How much do you think an oxygen sensor of the bank 2 ll cost and also the spacer. my email is ibisyerdig@yahoo.com i'm waiting for your response please

You don't need a new converter. Gut out the old one before it disintegrates completely. It's blocked and that's why your fuel economy is poor. Then fix the spacers on the oxygen sensor before installing them back into the pot.

@ nissan part. Will this Spacer work on my 1996 Toyota camry which uses 2 sensors for both upper and lower chambers. Please forward cost, contact and usuage procedure to my box @ issy1500@yahoo.com

Thanks

nissparts: You don't need a new converter. Gut out the old one before it disintegrates completely. It's blocked and that's why your fuel economy is poor. Then fix the spacers on the oxygen sensor before installing them back into the pot.

@Nissparts, can you share more on this?

nissparts: Oxygen sensor spacers available!

How much is the spacer, I currently have this code P0421-Warm up catalyst Efficiency below threshold.

nissparts: Oxygen sensor spacers available!

How much is the spacer,I currently have this code P0421-Warm up catalyst Efficiency below threshold.

A spacer is N5000

Issy, you have mail

If anyone needs a pictorial description of this process, drop your email and I'll send it to you. It's a word document with pictures and too heavy to upload here.

nice job. this is a very educative post.

nissparts: If anyone needs a pictorial description of this process, drop your email and I'll send it to you. It's a word document with pictures and too heavy to upload here.

@Nissparts, please send to hullhubs304@gmail.com

Sent

Over time, that foamy/netty substance either gets clogged or breaks up in pieces. This results in different issues
When clogged, the following occurs
Engine hesitation (for example the car will struggle to climb a hilly road)
Engine pinging on acceleration
Bad fuel economy because the engine has to work harder to move the car since the exhaust cannot breathe
Engine overheating

When it breaks up into pieces, the following occurs
Engine eats oil
Engine damage(complete)



bros, infact u deserve some rounds of beer for this piece..very educative...You just described what my Honda CRV 98 model is doing...except for the overheating, every other thing u mentioned here is happening to my car. I noticed that climbing a hill it sounds like if the engine is not getting enough power..when driving, the engine will jerk just like changing gear under a second and continue as if nothing happened..and the fuel economy?..hmmm, on the average i use like 20 litres under 2 days....i checked out the port u described here & noticed that mine has been cut & welded back...so how do i check if the catalyst is still there or has been removed?..secondly, can u give me an idea of the cost of a catalyst and converter for my car make * model?...God bless u real good bro!

Hello Princedant, there's no way to know for sure except you take it off to have the insides checked.
A brand new replacement will run you about N50k

nissparts: If anyone needs a pictorial description of this process, drop your email and I'll send it to you. It's a word document with pictures and too heavy to upload here.

kindly drop:oyinlanz@yahoo.co.uk. Thanks

Sent

niyo_zanl:

kindly drop:oyinlanz@yahoo.co.uk. Thanks

pls send to prince24_7_365@yahoo.com
txs a lot.

Sent to you

Very educative write up.pls I'm inttested etimoqua@gmail.com

Sent

..

@ Segeb,

The front catalyst is 80k and the rear is 40k for brand new.

Cant get an intermediate shaft sensor