That was back in the days when the longevity of O2 sensors were questionable and California was pushing for cleaner cars...smog?

Now days if they fail you get a check engine light.

Bosch still suggests a 100K life.....BUT in real life "most" live about 150K.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator