S 500 Sedan (140.051) V8-5.0L (119.980) (1996)
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The sensor ceramic is conductive for oxygen ions from approx. 300 degrees C. If the oxygen share varies greatly on both sides of the ceramic probe
body, a voltage (Nernst concentration cell) is generated on the friction planes by means of the particular properties of the ceramic probe body on the
friction plane. This is a measure for the residual oxygen content in the exhaust.
Faults at the O2 sensor can be detected by means of the O2 sensor signal.
Defined limit values must be maintained for the O2 sensor voltage, the duration of the period and for the sensor status change.
The O2 sensor signal has a steep voltage jump (at Lambda=1) at the transition from a rich (A) to a lean mixture (B). This property is utilized for the
lambda closed-loop control.
ME-SFI 1.0
The ground for the sensor signal at the ME 1.0 control unit is raised to approx. +0.71 V compared to the general vehicle ground.In the event of a short
circuit of the sensor signal to ground, the ME control unit thus switches the lambda closed-loop control to open-loop mode (average value). This
prevents a high fuel consumption.
ME 2.0, ME 2.1, ME 2.7, ME 2.8
