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Figure 14: UEGO Sensor Installation
POST-CATALYST OXYGEN SENSOR
The sensor installation point must be sufficiently tested by the customer for functionality and durability.
There shall be no possibility of exhaust leaks upstream of the sensor as exhaust pulsations can draw in
ambient air leading to erroneous measurements.
Installation in the exhaust line must be at a point guaranteeing representative exhaust gas composition
while also satisfying the specified temperature limits. The active sensor ceramic element heats up
quickly. This means that the sensor installation location must be selected to minimize exhaust-side
stressing with condensation water in order to prevent ceramic element cracking. This is helped by
locating the sensor on the outlet of the catalyst assembly.
Design measures:
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Locate sensor as close to the catalytic converter outlet as possible, without exceeding maximum
allowed temperature range
-
Attempt to achieve rapid heating-up of the exhaust pipes in the area in front of the sensor.
The exhaust pipe in front of the sensor should not contain any pockets, projections, protruding or
edges etc. to avoid accumulation of condensation water. A downside slope of the pipe is
recommended.
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The use of a sensor type with double protection tube can give a better protection of the sensor
ceramic against condensation water drops. In this case make sure, that the front hole of the double
protection tube does not point against exhaust gas stream.
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