I'd like to see your numbers, and the passing limits. (I'll give you a free analysis.) Also, what kind of test? List CO2 and 02 if available.

Most cars will run okay with a bad 02 sensor. On board diagnostics will pick up some failure modes, but not all. 02 sensors can get "lazy" with age and respond slowly, which can effect emissions. Modern OBDII systems might be able to pick this up, but not your vintage electronics.

You can eavsdrop on the O2 sensor with a scope and make a subjective analysis of its behavior.

Duke