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@Anan : Someone else may have a different idea, and if they do I hope they will speak up:

The most common failure I have seen in the catalytic converter includes it collapsing and making the car nearly impossible to drive, so I think that yours is okay.

My car indicated a possible bad cat, but it was the oxygen sensor after it that was actually bad. It is a gamble, but replacing the sensor is the first thing that i would try, and it will be much less expensive than the cat.

 

Thanks a lot John. How many oxygen sensors there are in my car and what are their GM part numbers? Which one should I change first?

 

In my case, for my 2.4 car, I eventually lost all power/get-up-and-go in the car after a couple of weeks from when the light first appeared. I would rev the car to 4k rpm, and the car would choke. I replaced mine. I was fortunate. Dr Dave at DDMworks had the part laying around his shop.

It was interesting too in that I gradually lost all sound in my magnaflow muffler.

 

If the car is running well, I would replace the downstream oxygen sensor first. MUCH cheaper and might solve the problem.

 

Might I suggest that if you suspect an issue with either one of the oxygen sensors that you test it first before replacing it. No need to just throw parts at it.

 

The cat can overheat and catch fire if it's plugged up bad enough.

 

And what do you suggest that I do? So far the car drives fine.

 

if it's driving fine with normal power levels I would look for exhaust leeks,cracked ex manifold etc. if all is good there, make sure air filter is good,run some good fuel system cleaner through a few tankfulls.then a o2 sensor replace. if you can buy from ebay that may be a choice,Ive bought from israel before, it should go both ways but not always. if there is another neerby country you can drive to that can change the parts at a price that makes it worth it that may be a option. kinda hard to say from hear.... a leek between the cat and the exhaust can throw a code.or a leek in the exhaust system somewhere else may do it.

 

There are two sensors on an NA before and after the cat either one will trigger the bad converter code .Don't know how sophisticated your mechanics test equipment is if it's on the basic side it will read this as a bad convertor . I had this issue a few years ago and went to the local auto parts store as I was out of town and got the same result . They recommended I take the car to a shop (Joe Stamell's in Farmington Hills I'll give this guy a free plug anytime I can for the great service he gave me )with better diagnostic equipment and he was able to pinpoint the problem as the aft O2 sensor $78.00 for a genuine GM part and 50 minutes later I was on my way . To add you can replace these yourself you will just need a special O2 socket to remove them here in the states the socket is less than 10 dollars .

 

Is there a difference in the upstream and downstream 02 sensor or are they interchangeable?

 

Well...guess I learned something. I thought the NA only had one.

 

I seem to remember that some of the 06s had issues with the Cat? They failed early. GM did a recall and extended the warranty period beyond 8 years if I recall correctly. Take your VIN to GM and see if your car falls into the recall set and see if they already replaced it.

Shoving cleaner into the car and expecting that to fix a cat error code would make me question the competency of the tech. Just saying.