Mitsubishi FUEL Manual page 121

Code No. P0155 Oxygen sensor heater (front) system
<Bank 2 sensor 1>
Range of Check
D The engine coolant temperature is approx. 20_C or more.
D The oxygen sensor heater (front) remains on.
D The engine speed is 50 r/min or more.
D Battery voltage is 11 - 16 V.
Set Conditions
D The current, which flows through the oxygen sensor heater (front), is 0.2 A
or less or 3.5 A or more for six seconds.
Measure at left bank oxygen sensor
(front) connector B-106.
D Disconnect the connector and
measure at the harness side.
D Resistance between terminals 2
and 4
OK: 4.5 - 8.0 W
OK
Check the following connector:
B-106
OK
Measure at left bank oxygen sensor
(front) connector B-106.
D Disconnect the connector and
measure at the harness side.
D Ignition switch: ON
D Voltage between terminal 2 and
earth
OK: System voltage
OK
Measure at engine-ECU connector
C-168.
D Measure the voltage at the
engine-ECU terminal.
D Ignition switch: ON
D Voltage between terminal 3 and
earth
OK: System voltage
OK
Check the following connector:
C-168
OK
Check the harness wires between
the left bank oxygen sensor (front)
and the engine-ECU and between
the left bank oxygen sensor (front)
and the engine control relay.
OK
Check the trouble symptoms.
NG
Replace the engine-ECU.
MPI <6A1> -
Troubleshooting
NG
Replace
NG
Repair
NG
Check the following connector:
C-31
Check the harness wires between
the left bank oxygen sensor (front)
and the engine control relay, and
repair if necessary.
NG
Check the following connector:
C-168
Check the harness wire between the
left bank oxygen sensor (front) and
the engine-ECU, and repair if
necessary.
NG
Repair
NG
Repair
OK
Transient malfunction
(Refer to GROUP 00 - Points to
Note for Intermittent Malfunctions.)
Probable cause
D Malfunction of left bank oxygen sensor heater
(front)
D Open or short circuit in the left bank oxygen
sensor heater (front) circuit or loose connector
contact
D Malfunction of engine-ECU
NG
OK
NG
OK
13A-121
Repair
Repair