Catalytic Converter Catastrophe

My wife owns a 1996 Camry 4 cylinder automatic with 170k miles. About a year ago, she noticed an exhaust pipe had rusted through and took it to the mechanic. The informed us that it was the flex pipe that was rusted and that, unfortunately, it had a catalytic converter welded to it. The replacement flex pipe could only be ordered with another cat attached to it to prevent someone from just replacing the pipe and not the cat. I have problems with this logic but I’ll try to keep this short. So he replaced the whole thing, $436 for parts that he claims were factory and another $123 for labor. Who knows if there was anything wrong with the cat, since the problem was the rusted pipe.

Okay, eleven months later the engine light comes on. We take it in and they claim that the problem is that the SECOND catalytic converter has gone out. This one is attaches to the exhaust manifold. It’s either welded to the manifold or welded to another pipe, I can’t remember which exactly. But in either case, once again it’s a kit and the cost is $398 for the factory parts and about $270 for the labor.

He says he knows it the cat because there is a sensor before and after it and they are giving the same reading, hence the cat isn’t doing anything. This is where it gets complicated.

I called around and got some second opinions on the phone. I talked to one particular shop that seemed very knowledgeable and was willing to go in-depth on the phone.

The second mechanic claimed that there was no such two sensor setup on the first catalytic converter. They said that’s how the catalytic converter attached to the flex pipe works. So there’s a conflict between the two already. Secondly, they say the it should cost $825 in parts for the factory flex pipe+cat. Our mechanic charged only $436 and they claim upon double-checking that yes, they are factory parts.

The other conflict is that our mechanic says yes, catalytic converters do just “go bad” on cars eventually, the second mechanic says that no, they only go bad if there’s some other problem and you need to track that down rather than just treat the symptom. This is a bit more of a philosophical point, but just laying it out there.

The second mechanic claims the exhaust manifold connected cat (she called it a pre-cat) should only be about $208 for factory parts. Another discrepancy.

Now, the big difference between the two is that our mechanic is working on the car and the second mechanic has never seen our car. She has also not necessarily worked on a catalytic converter for the same model of Camry. So she’s going off what she has on paper/computer and what Toyota tells her. Our mechanic pointed out all the various parts on the car and showed us the flex pipe with converter.

So, is this a case of the information the second mechanic getting being wrong? Is our first mechanic flat out lying when they say the exhaust manifold-connected cat has sensors on both sides? Is there yet another third answer to the whole situation?

I’d really appreciate any comments the community has. I should note that both these mechanics are very highly rated on the mechanic files. We’ve gotten a lot of work done in the past on both her car and my car at this place. Then again, you could read that another way and say we’ve just been ripped off a lot already…

It appears that your 4-cylinder Camry actually does have two converters, a forward and an aft, and that there is one oxygen sensor in the foreward coverter assembly and the second in the aft section of the aft converter. I can only speculate that this is a “transitional” design intended to modify the 1995 system to meet the new 1996 OBDII requirements. OBDI systems only needed one oxygen sensor, OBDII systems needed a secnd to monitor the performance of the converter itself.,model:Camry,year:1996),AND(universal:1))&Vi=11784+4294963459+1725&y=1996&mk=Toyota&md=Camry

Yes, no change in the readings from the first and second oxygen sensors is exctly how the ECU knows the converter has gone bad.

That price difference in the exhaust part replaced would not be uncommon. Dealers will typically charge about twice the price of a parts store for what is essentially the same part.

And yes, converters can go bad, especially on high mileage cars. The catalyst inside the converter can become coated with the accumulated residue from oil usage that would be normal for a high mileage vehicle and discontinue it’s ability to function. The catalyst needs to be able to contact the NOx molecules directly, and a coating can prevent that.

Remember that the first repair was due to a rusted pipe, not a failed converter. It is entirely possible that the aft converter has failed simply due to the aforementioned residue.

As strange as it sounds, I don’t think either is being dishonest or is incorrect. And I don;t think their statements are incompatsble.

Guys, why do I feel so weird making this post?

Thanks so much for the reply. Got a few questions, though.

Am I reading you right in you saying it works like this:
engine—sensor1-----cat1-----flex pipe----cat2-----sensor2—tailpipe

If it’s that, then there’s really no way of saying that it’s the first cat or the second, right? Other than the fact that the second cat is very new, of course. I’m having a little time figuring out what you mean by “in the forward converter assembly”.

For the pricing, both price quotes are coming from the mechanics. They’re both quoting me how much it would cost for them to do the repairs in parts. While I know some mechanics mark up parts more than others, this seems a huge discrepancy. We’re also talking about all factory parts, no aftermarket stuff.

When you say it’s possible that the aft converter has failed, I’m also a little puzzled. This is the new converter that was put on with the flex pipe. It would have only been on there for the last year. Is it likely that it would fail in such a time? Maybe this is just more confusion on my part in how you’re using the terms aft and forward.

That’s my understanding after looking up the parts.

Apologies. The confusion was at my end. I thought it was the front section that had been replaced.

If you go to the link I supplied you’ll see that the same original equipment replacement parts gor for prices that vary by a factor of 100%. That’s normal. And dealers charge far more, simply because the parts had to be stamped with the Toyota part number and go through their inventory and distribution system…then get marked up by the dealer. Independent mechanics get a direct parts store price and then a shop discount that can range up to 20%. So, it depends on where the mechanic gets his parts from. Dealers are always more expensive.

Ask around and try to find a reputable exhaust/muffler shop. They are better than general shops and fabricating replacement parts that can get you out the door for a lot less money. I have a very good general mechanic shop, but they don’t do exhaust work at all. He sent me to “Curtis” twice a few years ago.

When I was calling around, all the mechanics I talked to said they won’t use aftermarket catalytic converters because they often don’t talk to the computers properly, causing future false-alarm error codes to be transmitted. Do you think that’s not the case? I assume when you were talking about fabricating parts you meant something other than the factory parts. I’m not very knowledgeable about auto parts so I may be getting some of that wrong.

So it’s right according to my diagram? They’re only guessing it must be the first catalytic converter because the other one was replaced so recently?

And as far as the parts, I’m still a bit confused. The second mechanic was both twice as expensive on the quite for fixing the cat2 and half as expensive on fixing the cat1. It would seem weird that they’d be so inconsistent. Neither of these mechanics are dealers, btw, though I understand that you’re saying they may be buying their parts from dealers.

Is an OEM part the same as a factory part? Is a “factory part” just an OEM part that Toyota puts their part number on? So what’s an “aftermarket” part as opposed to an OEM part? As I stated below, all the mechanics I talked to liked aftermarket parts except for on catalytic converters because they said they’d had problems in the past with the talking to the computer properly.

You got stroked on the first repair. I ran into this same issue with my '03 Camry. When I was told the cat and flex pipe were one unit, I started looking at options. I actually bought a flex section and was getting ready to weld it myself when I called around and found a local Meineke that had seen so many of these they make their own flex to cat pipe that does not require a new cat. $125 TOTAL for the replacement pipe. Something to consider next time…

The order of the cat converters and sensors is right, but I’m unsure about where the flex pipe is.

There are “Factory parts”. Those are OEM parts labeled with the car manufacturer’s labels and sold only through the car manufacturer’s distribution system (from dealers).

There are OEM parts (original equipment manufacturer) who are the same people that make the parts for the auto manufacturer. They can be purchased at parts stores.

There are “direct fit” OEM Replacement parts, that are the same configuration and design as the OEM parts, but less expensive. They install the same and are generally exact copies of the OEM parts.

There are “aftermarket” parts that may or may not fit well and may or may not work as well as the OEM parts.

There are generic parts that can be installed in a range of vehicles and generally require creativity in installation.

Then there’s Midas. They weld in whatever they have on the shelf.

NOTE: there is “gray area” between OEM Replacement parts and aftermarket parts. One needs to be careful.

The response you got from the mechanics may have been based on how the question was worded. I’ve yet to meet a mechanic that feels uncomfortable putting an an OEM Replacement cat connverter.

I had a look at my 1996 Camary with the 5S-FE engine. The precat O2 sensor is in the exhaust manifold ahead of the main cat and the post O2 sensor is down on the exit end of the same cat. If you open the hood of your car you will see the catalytic converter right in front of the engine (covered by heat shields). There will be a spark plug looking probe sticking out fairly high with two wires coming out. Down lower behind the radiator will be the second O2 sensor looking the same with two wires also coming out. That whole cast iron piece the O2 sensors are bolted to is the front Catalytic Converter. That is the only one the two O2 sensors are monitoring. So if you have the dreaded P0420 code that is what you have to replace. It appears on mine that the cast iron parts are bolted together so I am wondering if the CC element can be accessed and replaced separate from the shell.

The flex pipe, the small catalytic converter and, it appears, the front muffler are all one piece and bolted by a flange to the exit of the front CC. Since the efficiency of this CC is not monitored, you most likely do not need to replace it. I think this CC was a sort of cleanup CC used to bring the emissions down to ‘extremely low emission vehicle’ levels.

Let us know what you do; what the replacement costs come out to be; and any other interesting details that we can add to our knowledge.

Any update on this thread? In same boat with my 2000 4cyl on another thread. Primary converter showing up as bad. way too much money to invest in a 10 year car. seems a lot of failures out there and the aftermarket parts don’t have a long warrantee.