O2 sensors: can they malfunction intermittently?

[dr-rjp]

I have heard that it is possible for bad O2 sensors to not throw a code.

Is this true??

[elwesso]

most of the time they dont throw a code... Theyre assumed to be bad after 60-120k...

Most times if they get sluggish they throw an injector leak code...

[Road Ruler]

On our Nissan Quest mini van the engine would not run when the O2 sensor went bad. In 14 years and 400,000klm's we have had the van towed twice because the O2 sensor went flat. The vehicle would start, run rough, but not rev higher than 1,500 rpm. Change the sensor and all is well, till the next time.