Removal - Upstream 1/1, 2/1; Removal - Downstream 1/2, 2/2 - Dodge Intrepid Service Manual

14 - 34 FUEL INJECTION
O2 SENSOR (Continued)
fuel mixture) the sensor produces a voltage as high
as 1.0 volt. By monitoring the oxygen content and
converting it to electrical voltage, the sensor acts as
a rich-lean switch.
The heating element in the sensor provides heat to
the sensor ceramic element. Heating the sensor
allows the system to enter into closed loop operation
sooner. Also, it allows the system to remain in closed
loop operation during periods of extended idle.
In Closed Loop, the PCM adjusts injector pulse
width based on the upstream heated oxygen sensor
input along with other inputs. In Open Loop, the
PCM adjusts injector pulse width based on prepro-
grammed (fixed) values and inputs from other sen-
sors.
DOWNSTREAM OXYGEN SENSOR
The downstream heated oxygen sensor input is
used to detect catalytic convertor deterioration. As
the convertor deteriorates, the input from the down-
stream sensor begins to match the upstream sensor
input except for a slight time delay. By comparing
the downstream heated oxygen sensor input to the
input from the upstream sensor, the PCM calculates
catalytic convertor efficiency. Also used to establish
the upstream O2 goal voltage (switching point).
REMOVAL

REMOVAL - UPSTREAM 1/1, 2/1

The engines uses two heated oxygen sensors, one
in each exhaust manifold.
CAUTION: When disconnecting the sensor electrical
connector, do not pull directly on wire going into
sensor.
(1) Remove the negative battery cable.
(2) Disconnect the heated oxygen sensor electrical
connector.
(3) Use a socket such as Snap-On YA8875 or a
crow foot wrench to remove oxygen sensor (Fig. 21).

REMOVAL - DOWNSTREAM 1/2, 2/2

The O2 sensors are located at the outlet ends of
the catalytic converter (Fig. 22).
WARNING: THE EXHAUST MANIFOLD, EXHAUST
PIPES AND CATALYTIC CONVERTER BECOME
VERY HOT DURING ENGINE OPERATION. ALLOW
ENGINE TO COOL BEFORE REMOVING OXYGEN
SENSOR.
(1) Remove the negative battery cable.
(2) Raise and support the vehicle.
Fig. 21 Upstream Heated Oxygen Sensor 1/1
1 - PROPORTIONAL PURGE SOLENOID
2 - O2 SENSOR
Fig. 22 Downstream Heated Oxygen Sensor 1/2
1 - OXYGEN SENSORS
(3) Disconnect the wire connector from the O2 sen-
sors.
CAUTION: When disconnecting the sensor electrical
connector, do not pull directly on wire going into
sensor.
(4) Remove the O2 sensors. Snap-On oxygen sen-
sor wrench (number YA 8875) may be used for
removal and installation.
LH