Besides the obvious codes to indicate failure of a B1 or B2 NBO2 sensor, are there any indicators that one is going bad? Do they "degrade" or just "fail"?

If you were bumping 90K miles on the originals would there be any REAL...IMMEDIATE benefit in replacing them?

 

Sometimes when they are going bad the readings can be "lazy". If you have a scanner you can watch the O2 voltage fluctuate from +- 200-800mv radidly. So fast that you can't really pick out a single value at any instance. If the voltage fluctuates slowly then you probably have a bad O2 sensor. I've put over 200k on mine.

 

Thanks! I appreciate the info.