Is it safe for the health of the engine to drive without fixing an 02 sensor & with broken catalytic converter

Question

if a malfunction indicator light on a chevy cavalier is on

and if the 02 sensor behind the catalytic converter is broken, does this entail that the converter must be repaired for the 02 sensor to work properly if one or both of these are broken? And most importantly, for how long can this car be driven without fixing these?

Answer 1

For the sake of the environment you should repair the vehicle as soon as possible.  

The secondary O2 sensor ( the one after the catalytic converter, nearest the muffler ) is responsible for monitoring the efficiency of the catalytic converter.  If the sensor is faulty it doesn't automatically mean that the catalytic converter is faulty as well.  

Faulty catalytic converters can cause excessive HC's and NOX to be emitted from the tailpipe.  A shop with a smog machine can determine if the cat is bad or not.  

You can probably drive the vehicle forever this way ( depending on your smog check laws )  BUT as I said before, for the sake of the environment you should repair the vehicle.

The secondary o2 doesnt change fuel mixture.  it only monitors the cats performance.

Answer 2

With the sensor broken I would assume that you are getting bad mileage and possibly smoking. After driving this way for a few months the catalytic converter will probably end up clogging and need replacing as well. I would fix soon