Check Engine (error 2 lambda) - Toyota Celica, 1.8 liter, 2000

I think for owners of the 230 Selick Check Engine is quite commonplace. Most often - low-quality gasoline, well, and 2nd place, perhaps, is occupied by an error of 2 lambdas :) The one after the catalyst. The reason is low-quality fuel, as a result of which it fails, and 2 lambda gives an error, as a result, the Check lights up. Exit 2:
1) Replacing the catalyst. But the fact is that the original is very expensive, besides, the goods are in short supply. Used is impossible to find. Or, as an option, install a universal one (cost from 80 to 150 ye, for the most budget options.
2) Cut out the catalyst, weld a stronger / flame arrester instead.

But, if you use option 2 (which is the most budgetary), of course, 2 lambda will continue to give an error of a non-working catalytic converter, which is why they make a "trick" on this very 2 lambda.
The exception is right-handed Japanese women, they have only 1 lambda, so you don’t need to bother with trickery.

Naturally, my check was also on fire. First I replaced 2 lambdas, didn't help. Then, already counting the errors, it became clear that the catalytic was dead (in other words, it crumbled). I already had not my own, but a universal catalytic converter, which was enough for 2.5 years. In addition to the error, a characteristic ringing was observed in the range of 2000-2500 rpm.

Of both options for solving the problem, I chose 2. I replaced the catalytic converter again with a universal one. I didn’t want to install a decoy and a flame gas, since obviously without a catalytic converter the exhaust sound will become louder (I am quite satisfied with the regular sound). YES, and in general, I believe that everything should be as provided by the manufacturer.

The check no longer burns, the ringing is gone - beauty.
Combined everything with changing the oil in the engine. The next step is to change the oil in the automatic transmission, drive belt, roller and crankshaft oil seal.