MPI <4G63>
ï
On-vehicle Service
13D-100
Oxygen sensor (rear)
1.
Disconnect the oxygen sensor connector and connect
the special tool test harness (MB991658) to the connector
on the oxygen sensor side.
2.
Make sure that there is continuity (11
ï
18
:
at 20
˚
C)
between terminal No. 3 and No. 4 on the oxygen sensor
connector.
3.
If there is no continuity, replace the oxygen sensor.
4.
Warm up the engine until engine coolant is 80
˚
C or higher.
5.
Perform a tracing for 5 minutes or more with the engine
speed of 4,500 r/min.
6.
Connect a digital voltage meter between terminal No.
1 and No. 2.
7.
While repeatedly racing the engine, measure the oxygen
sensor output voltage.
Standard value:
Engine
Oxygen sensor
output voltage
Remarks
When
racing the
engine
0.6
ï
1.0 V
If you make the air-fuel ratio
rich by racing the engine
repeatedly, a normal oxy-
gen sensor will output a
voltage of 0.6
ï
1.0 V.
Caution
D
Be very careful when connecting the jumper wire;
incorrect connection can damage the oxygen
sensor.
D
Be careful the heater is broken when voltage of
beyond 12 V is applied to the oxygen sensor
heater.
NOTE
If the sufficiently high temperature (of approximately
400
˚
C or more) is not reached although the oxygen sensor
is normal, the output voltage would be possibly low
although the rich air-fuel ratio. Therefore, if the output
voltage is low, use a jumper wire to connect the terminal
No.3 and the terminal No. 4 of the oxygen sensor with
a (+) terminal and (
ï
) terminal of 12 V power supply
respectively, then check again.
8.
If the sensor is defective, replace the oxygen sensor.
NOTE
For removal and installation of the oxygen sensor, refer
to GROUP 15
ï
Exhaust Pipe and Main Muffler .
Oxygen sensor
(rear)
Oxygen sensor
(rear) connector
Equipment side connector
MB991658
Oxygen
sensor