SLK 320 (170.465) V6-3.2L (112.947) (2002)
O2 Sensors, Function
1
Sensor ceramic
2
Electrodes at boundary surfaces
3
Exhaust pipe
Arrows
black: exhaust gases
white: outside air
The sensor ceramic is conductive for oxygen ions from approx. 300 °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.
Curve of O2 sensor voltage, schematic
A
minimum sensor voltage (lean mixture)
B
maximum sensor voltage (rich mixture)
C
Lower limit value for work measurement
D
Upper limit value for work measurement
E
Duration of sensor state change for lean-rich transition
F
Duration of sensor state change for rich-lean transition
G
Duration between sensor state change
H
Threshold for rich range (e.g. greater than 475 mV)
I
Threshold for lean range (e.g. less than 425 mV)