Mitsubishi Eclipse 1990 Service Manual page 449

Scan tool 126
Code General scan tool Downstream
No. 38
21
[Comment]
Background
Downstream heated oxygen sensor requires a heater circuit for proper operation.
The heater circuit is supplied with battery voltage through the
A failure in the sensors heater circuit prevents it from providing accurate data to the
If the PCM monitors more than 1.2 volts, the sensor has shorted to heater circuit voltage.
Range of Check
Two or more minutes after the engine starts
Engine coolant temperature:
Set Condition
Heated oxygen sensor output voltage is more than 1.2
Check the heated oxygen sensor (rear). (Refer to
Check the following
Check trouble symptom.
Check the harness wire between the PCM and the heated
sensor (rear) connector.
Replace the PCM.
Scan tool 128
Code General scan tool Closed Loop Temperature
No.
17
[Comment]
Background
The fuel control system remains in open loop due to low engine
This DTC will be stored if engine temperature remains
of operation and no engine coolant temperature sensor code has been set.
Range of Check
Engine: running
Set Condition
Engine coolant temperature does not exceed
since starting the engine.
Check the thermostat. (Refer to GROUP 14
Check the following connectors:
Check trouble symptom.
temperature sensor connector.
(NON-TURBO)>
Voltage
or more
OK
OK
NG
OK
after 10 minutes have passed
Thermostat.)
OK
OK
TSB Revision
Shorted to
relay relay).
for 3 seconds.
NG
R e p l a c e
NG
Repair
NG
for 10 minutes
NG
Replace
NG
Replace
NG
Repair
Heated oxygen sensor failed
harness and connectors
Thermostat fully open
Engine coolant temperature sensor
Engine coolant temperature sensor
improperly connected
PCM failed,
,
.
,
,