Service & Repair Manual

24-76
Oxygen sensor control,
checking
Oxygen sensor control, function
Notes:
The oxygen sensors compare the oxygen
content of the air with residual oxygen content in
exhaust and deliver a voltage signal to the
control module.
The voltage signal "mixture rich (too little residual
oxygen)" is approx. 0.7 to 1.0 V.
The voltage signal "mixture lean (a lot of residual
oxygen)" is approx. +0.0 to 0.3 V.
At the transition from "rich" to "lean" and vice-
versa ( = 1.0) voltage will jump from 0.7 to 1.0
V to 0.0 to +0.3 V (or viceversa).
Due to the steep voltage jump, oxygen sensor
control cannot maintain the ideal mixture of =
1.0 as constant. Oxygen sensor control
constantly fluctuates back and forth between the
conditions "slightly too lean" and "slightly too
rich".
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