You cannot unclog a converter. If it is clogged it much be replaced.
Replace the Downstream O2 sensor (after the catalytic converter)
Crawl under the vehicle and look up. It is mounted in the exhaust system behind the engine.
The install is the same as a muffler. A muffler shop can do it cheaper than anyone else.
o2 sensors are in the exhaust Usually in front of the catalytic converter near or in the exhaust manifold.
Catalytic converter I think The 02 Sentra doesn't have a "regular" catalytic converter, its an all in one manifold converter assembly. *There are 4, they are located in the exhaust manifold. On the 02 Sentra 1.8 there are two wiring harnesses that have blue plugs and two that have green. Those are the harnesses for the Oxygen sensors. Follow the harness down the manifold and that's where they are located.
Replace the Downstream O2 sensor (after the catalytic converter)
2
one
2. one on the exhaust manifold under the hood, 1 on the exhaust pipe just after the catalytic converter under the car
a low whistling noise every time you release the gas pedal usually coincides with a dieing catalytic converter Rattle, check engine light, stalling problems, low power, strange exhaust odor,
The CC is attached to the manifold/exhaust. It doesn't "need maintenance". But it might need to be replaced, which could get a little pricey.
The are two o2 sensors in an 04 Sentra. One is called the front sensor, and it is in the engine compartment, in the exhaust manifold. The other, the rear one, is in the exhaust pipe under the car, past the catalytic converter.