F*ck my mechanic...

[dyeagain15]

Ok year make model engine? and we'll be squared away

[Wastehog]

I would also call your o2 sensor, like Kandiman said. They are usually easily to be defective. Cats are kind've hard to mess up building, but it can be.

Off topic, Not all mechanics are trying to rip you off, but they usually do. If you want quality work, go to a major chain. They usually care about customer satisfaction, and will go to great lengths to keep the reviews positive. Unlike your average Joe blow, he couldn't care less if one customer hates him.

IMO If you can, do your own work. You don't need a lift.. you need jacks and jack stands. 2 and 4 post lifts are a luxury not a necessity to work on your car. Suck it up and do it your self. You will have gratification when you fix it your self and blow the money you saved on audio equipment.

P.S. Internet is your friend.. there's almost always someone who had the same problem as you. Fix it yourself and take pictures

[dyeagain15]

Well it depends on which O2 sensor it is, if its the upstream one then yea its O2, but if its after the cat then it doesnt rule out the possibility of the cat, but i find it hard to believe after putting a new one in, it'd go to shit like that. Hell it might just be throwing a code because the difference between the two cats. The readings could be diff than the stock settings in the computer.

[toytrkdrvr]

It could be one simple thing or several things. He probably looked at the code and guessed that the cat was the problem. It will be impossible for anyone to say whats wrong without looking at the engine data as the engine is running.

If you want to diagnose it yourself, you would need to check the signal wire from the O2 sensors with a voltmeter but an o-scope would be better.

You said 600.00 for the cat and other repairs, what were the other repairs?

I've seen some cheap throw-away cats get put on and still fail smog checks.

Some newer cars today do not like the aftermarket O2 sensors and will keep the engine light on, just be aware of this.

You are better off going to another repair facility and getting it checked out. I would recommend that you find a AAA certified shop, they have to pass inspections on quality and such every year. But that is no guarantee that they will be honest.

Do not let the first shop get away with this. From your location I would guess New York. In California we have the bureau of automotive repair. IF my googling is correct yours is run by the DMV. Contact them and file a complaint and contact the Better Business Bureau and file a complaint there too.

Good luck.

[ktm300]

Get 02 sensor readings, from all of them. Compare to OE spec, check the temp of the cat....exhaust all your options before spending another $500 on another cat.

[SlowLoudNBangin]

one word:

new mechanic