Q: How long can I drive with bad 02 sensor? 1996 Audi A4

HI there - possibly. If it is one of the pre-catalytic converter oxygen sensors, yes, it is possible to damage the catalytic converters. From the problem codes, this would be a "Bank 1/2, Sensor 1" - the operative information that it is Sensor 1". An oxygen sensor that was reporting a lean condition to engine management would cause the fuel injection to deliver a richer mix than the engine needs, passing unburned gasoline to the catalytic converter. This will, over a relatively short period of time, clog the converter(s). Converters are much more expensive than the oxygen sensors. Post-catalytic converter oxygen sensors (Sensor 2) report on how efficient the catalytic converter is doing its job. I recommend an oxygen sensor replacement performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.