Oxygen Sensor (E320)

These vehicles use 2 oxygen sensors. The oxygen sensors measure residual oxygen in exhaust gas. The oxygen sensors send a voltage signal to engine control module. The engine control module uses oxygen sensor voltage to control fuel injection.

O2S 1 is located before the catalytic converter in the exhaust system. O2S 2 is installed in the exhaust system after the catalytic converter. The function is identical to O2S 1. However, O2S 2 signal is used to monitor the efficiency of the catalytic converter and function of O2S 1.