Mitsubishi Montero (2004+). Manual - part 206

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-311

DTC P0155: Heated Oxygen Sensor Heater Circuit (bank 2, sensor 1)

TO PCM

TO PCM

WHITE-

BL

ACK

WHITE-

BL

ACK

AK201136

RED

BL

UE

LEFT BANK HEATED
OXYGEN SENSOR (FRONT)

4

1 2
3

B-22X

3

2

4

1

BATTERY

1

3

2

4

10

MFI
RELAY

POWERTRAIN
CONTROL
MODULE (PCM)

4

3

1 2

B-26

MU802665

Left Bank Heated Oxygen Sensor (front) Heater Circuit

1

2

3

5

6 7 8 9

4

20

21 22

232425

2627

10111213

14 15

16 1718

19

D-132

(MU803802)

AK201039

MFI RELAY

B-22X

AB

CONNECTOR: B-22X

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-312

.

CIRCUIT OPERATION

• Power is supplied from the MFI relay (terminal 

No. 1) to the left bank heated oxygen sensor 
(front) heater.

• The PCM (terminal No. 10) controls continuity to 

the left bank heated oxygen sensor (front) heater 
by turning the power transistor in the PCM "ON" 
and "OFF".

.

TECHNICAL DESCRIPTION

• The PCM checks whether the heater current is 

within a specified range when the heater is ener-
gized.

.

DESCRIPTIONS OF MONITOR METHODS
Left bank heated oxygen sensor heater (front) cur-

rent is out of specified range when engine coolant 
temperature is over 20

°C (68°F).

.

MONITOR EXECUTION
Continuous

.

MONITOR EXECUTION CONDITIONS (Other 
monitor and Sensor)

Other Monitor (There is no temporary DTC stored 

in memory for the item monitored below)

• Not applicable

Sensor (The sensor below is determined to be 

normal)

• Engine coolant temperature sensor

.

AK201277

CONNECTOR: B-26

B-26(GR)

AD

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

AK201038

CONNECTOR: D-132

AB

PCM

D-132(GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-313

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

• 60 seconds have elapsed from the start of the 

previous monitoring.

• Engine coolant temperature is higher than 20°C 

(68

°F).

• While the left bank heated oxygen sensor (front) 

heater is on.

• Battery positive voltage is between 11 and 16.5 

volts.

Judgment Criteria

• The left bank heated oxygen sensor (front) heater 

current has continued to be lower than 0.16 
ampere or higher than 7.5 ampere for 4 seconds.

.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Procedure 6 

− Other Monitor 

P.13A-4

.

.

TROUBLESHOOTING HINTS (The most likely 
causes for this code to be set are: )

• Left bank heated oxygen sensor (front) heater 

deteriorated.

• Open or shorted left bank heated oxygen sensor 

(front) heater circuit or harness damage.

• Connector damage.

• PCM failed.

START

END

YES

YES

YES

YES

NO

NO

NO

NO

MALFUNCTION

GOOD

CONTINUOUS

FAILURE FOR 4secs

MONITORING

CONDITIONS

CURRENT < 0.16A

CURRENT > 7.5A

AK302934

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-314

DIAGNOSIS

Required Special Tool:

• MB991316: Test Harness Set

STEP 1. Check harness connector B-26 at the left bank 
heated oxygen sensor (front) for damage.
Q: Is the harness connector in good condition?

YES : Go to Step 2.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 12.

AK201278

1

2

3

4

CONNECTOR: B-26

B-26(GR)

AC

HARNESS 
CONNECTOR: 
COMPONENT 
SIDE

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)