Mitsubishi MOTORS Space Runner 1999 Workshop Manual Supplement page 500

Code No. 59 Oxygen sensor (rear) system
Range of Check
3 minutes have passed after engine was started.
Engine coolant temperature is approx. 80_C or more.
Idle position switch: OFF
The throttle position sensor output voltage is 4.1 V or more.
Open loop control in operation
20 seconds have passed after deceleration finished.
Set conditions
The oxygen sensor (rear) output voltage is 0.1 V or less.
The difference in the maximum and minimum values for the oxygen sensor (rear)
output voltage is 0.08 V or less.
The oxygen sensor (rear) output voltage is 0.5 V or more.
The above conditions continue for a continuous period of 5 seconds.
Check the oxygen sensor (rear). (Refer to P.13B-73.)
Measure at the oxygen sensor (rear) connector D-22.
Disconnect the connector, and measure at the
harness side.
1. Voltage between 3 and earth (Ignition switch: ON)
OK: System voltage
2. Continuity between 4 and earth
OK: Continuity
Measure at the engine-ECU connector B-30.
Disconnect the connector, and measure at the
harness side.
Voltage between 54 and earth (Ignition switch: ON)
OK: System voltage
Check the following connectors:
B-30, D-22
Check trouble symptom.
Check the harness wire between the engine-ECU and
the oxygen sensor connector.
Replace the oxygen sensor (rear).
Check trouble symptom.
Replace the engine-ECU.
MPI –
NG
OK
1. NG
2. NG
OK
NG
OK
NG
OK
NG
NG
OK
NG
Troubleshooting
Probable cause
Malfunction of the oxygen sensor (rear)
Improper
short-circuited harness wire
Malfunction of the engine-ECU
Replace
Check the harness wire between the
oxygen sensor and the control relay
connector, and repair if necessary.
Check the following connector:
B-30
Check trouble symptom.
Check the harness wire between the
engine-ECU and the oxygen sensor
connector.
Replace the engine-ECU.
Check the following connector:
D-22
Check trouble symptom.
Repair
Check the harness wire between the
engine-ECU and the oxygen sensor
connector, and repair if necessary.
Repair
13B-19
connector contact, open circuit
NG
Repair
OK
NG
NG
Repair
OK
NG
Repair
OK
NG
or