®
(hot-wire type)
Intake
Air Temperature Sensor,
ELECTRONIC CONTROL SYSTEM
- Oxygen Sensor (Oz Sensor
)
ELECTRICAL CIRCUITR
Y
The electrical circuitry of the intake air
temperature
sensor is basically the same as that
of the water
temperature sensor
. See the
diagram for the electrical circuitry of the water
temperature sensor
.
OXYGEN
SENSOR
(
02 SENSOR
)
In order for engines equipped with the TWC
(three-way catalytic converter) to achieve the
best purification performance, it is necessary for
the air-fuel ratio to be kept within a narrow
range near the theoretical (stoichiometric) air-
fuel ratio
.
The oxygen sensor senses whether the air-fuel
ratio is richer or leaner than the theoretical air-
fuel ratio
. It is located in the exhaust manifold,
in the front exhaust pipe, etc
. (This differs
depending on the engine model
.
)
The following types of oxygen sensor are used
;
they differ mainly in the material used for the
element
:
• Zirconia element type
• Titania element typ
e
1
. ZIRCONIA ELEMENT TYP
E
This oxygen sensor consists of a element made
of zirconium dioxide (Zr02, a kind of ceramic)
.
This element is coated on both the inside and
outside with a thin layer of platinum
. Ambient
air is introduced into the inside of the sensor,
and the outside of the sensor is exposed to
exhaust gases
.
I
Flang
e
= Platinu
m
L- Zirconia elemen
t
Platinu
m
Protective
cover
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