There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
should be right above the catalytic converter, on the exhaust manifold
No, have the converter replaced.
They are replaced when they go bad.
Varies, a couple of weeks should be enough.
It should last the life of the car if you maintain the car as you should. Let the engine start running rich and do nothing to repair this condition and it will destroy the converter. But keep the engine tuned up and running as it should and you will never have to replace the converter. NEVER had a problem with my 1996 HONDA ACCORD engine and CATALYTIC CONVERTER needed to be replaced at 220,000 MILES.
The catalytic converter should be bolted onto the exhaust pipes. The bolts will have to be soaked in penetrating oil to be able to break them free, then you can replace the converter.
If the oxygen sensors for the 1991 Chevy 4.3 is running rich when it is warmed up it is best to have the sensors replaced. Once the sensors are replaced this should resolve the issue.
first up i would replace air filter and fuel filter then get engine tune up if nothing has been changed on vehicle, you should not have to change sensors
If and when it becomes clogged.
There should be two O2 sensors on that vehicle. The O2 sensors are threaded into the exhaust system, one before the catalytic converter and one after the catalytic converter.
onthere should be four of them. one is after the catylic converter. one is right before the catylic converter. the other two are on the motor.
Toyota's are very good about not leaking. Unless you have the transmission out there is no need to replace the torque converter seal. The rear main very rarely ever leaks.