where are located the s1b1 and s1b2
on 1998 Mercedes-Benz SL600

when i read my COBII i see the the output ov S1B1 is alweyes 0v is the sensor broken?

Asked by for the 1998 Mercedes-Benz SL600
Still have to check the sensors and the wiring. Upstream oxygen sensors are before the cats and the downstream are after the cats. How many miles on the car? Over 100K then you replace all since their useful life is over. 2hrs of labor and $850 in parts.