Mitsubishi Grandis. Manual - part 711

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-95

STEP 11. Check the trouble symptoms.

Q: Does trouble symptom persist?

YES : 

Replace engine-ECU <M/T> or 

engine-A/T-ECU <A/T>.

NO : 

Intermittent malfunction (Refer to GROUP 
00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

Code No. P0156: Cylinder 2, 3 Oxygen Sensor (Rear) System

OPERATION

• The sensor signal is inputted to the engine-ECU 

<M/T> or engine-A/T-ECU <A/T> (terminal No. 
116) from the cylinder 2, 3 oxygen sensor (rear) 
output terminal (terminal No. 4).

• The cylinder 2, 3 oxygen sensor (rear) (terminal 

No. 2) is earthed with engine-ECU <M/T> or 
engine-A/T-ECU <A/T> (terminal No. 96).

FUNCTION

• The cylinder 2, 3 oxygen sensor (rear) converts 

the concentration of oxygen in the exhaust 
emission into a voltage and inputs the signal to 
the engine-ECU <M/T> or engine-A/T-ECU 
<A/T>.

AK305557

9192

939495

96979899

100

105

113114

115116117

118119120

106

107108109

110111112

101102103

104

1

2

3

4

Cylinder 2, 3 oxygen
sensor (rear)

AB

Cylinder 2, 3 oxygen sensor (rear) circuit

Engine-ECU <M/T> or
engine-A/T-ECU <A/T>

B

G

R

From engine control relay

1

2

3

4

96

116

     B-18
MU802605

C-113

(MU803805)

Wire colour code
B: Black  LG: Light green  G: Green  L: Blue  W: White  Y: Yellow  SB: Sky blue  BR: Brown  O: Orange  GR: Gray
R: Red  P: Pink  V: Violet

To engine-ECU <M/T> or
engine-A/T-ECU <A/T>

5

C-115

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-96

• When the air-fuel ratio is richer than the 

theoretical air-fuel ratio, the cylinder 2, 3 oxygen 
sensor (rear) outputs a voltage of about 1 V. 
When it is leaner than the theoretical air-fuel 
ratio, it outputs a voltage of about 0 V.

• Based on this signal, the engine-ECU <M/T> or 

engine-A/T-ECU <A/T> corrects the deviation in 
the signal that is output by the cylinder 2, 3 
oxygen sensor (front).

TROUBLE JUDGMENT

Check Conditions

• Above 3 minutes later after the engine has 

started up.

• The engine coolant temperature is approx. 82°C 

or higher.

• The engine speed is 1200 r/min or more.

• The monitoring time is 5 seconds.

Judgment Criteria

• When the cylinder 2, 3 oxygen sensor (rear) 

output voltage is 0.2 V or less and a power 
voltage of 5 V is applied to the cylinder 2, 3 
oxygen sensor (rear) in the engine-ECU <M/T> 
or engine-A/T-ECU <A/T>, the sensor output 
voltage is 4.5 V or more.

• To be monitored once per driving cycle.

Check Conditions

• 2 seconds later after lack of circuit continuity is 

detected.

• When the cylinder 2, 3 oxygen sensor (rear) is 

normally operated.

Judgment Criteria

• When the air-fuel ratio is rich, the cylinder 2, 3 

oxygen sensor (rear) output voltage is 0.5 V or 
more.

• The cylinder 2, 3 oxygen sensor (rear) output 

voltage is less than 0.1 V.

• The maximum and maximum of the cylinder 2, 3 

oxygen sensor (rear) output is 0.078 V or less.

PROBABLE CAUSE

• Failed cylinder 2, 3 oxygen sensor (rear)

• Open/short circuit in cylinder 2, 3 oxygen sensor 

(rear) circuit or loose connector contact

• Failed engine-ECU <M/T>

• Failed engine-A/T-ECU <A/T>

DIAGNOSIS PROCEDURE

STEP 1. MUT-III data list

• Refer to Data List Reference Table 

P.13A-363

.

a. Item 69: Cylinder 2, 3 oxygen sensor (rear)

Q: Is the check result normal?

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

NO : 

Go to Step 2 .

STEP 2. Connector check: B-18 cylinder 2, 3 
oxygen sensor (rear) connector

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Repair or replace.

AK300977

1

2

3

4

AC

Connector: B-18

Harness side 
connector

B-18 (B)

Cylinder 2, 3
oxygen sensor
(rear)

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-97

STEP 3. Perform resistance measurement at B-18 
cylinder 2, 3 oxygen sensor (rear) connector.

• Disconnect connector, and measure at harness 

side.

• Resistance between terminal No. 2 and earth.

OK: 2 

Ω or less

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Go to Step 4 .

STEP 4. Connector check: C-113 engine-ECU 
<M/T> connector or engine-A/T-ECU <A/T> 
connector

Q: Is the check result normal?

YES : 

Go to Step 5 .

NO : 

Repair or replace.

AK300977

1

2

3

4

AC

Connector: B-18

Harness side 
connector

B-18 (B)

Cylinder 2, 3
oxygen sensor
(rear)

AK305616AB

Connector: C-113

<L.H. drive vehicles>

<R.H. drive vehicles>

C-113 (GR)

C-113 (GR)

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

Harness side connector

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-98

STEP 5. Check harness between B-18 (terminal 
No. 2) cylinder 2, 3 oxygen sensor (rear) 
connector and C-113 (terminal No. 96) 
engine-ECU <M/T> connector or engine-A/T-ECU 
<A/T> connector.

• Check earthing line for open circuit and damage.

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Repair.

STEP 6. MUT-III data list

• Refer to Data List Reference Table 

P.13A-363

.

a. Item 69: Cylinder 2, 3 oxygen sensor (rear)

Q: Is the check result normal?

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

NO : 

Replace engine-ECU <M/T> or 
engine-A/T-ECU <A/T>.

STEP 7. Perform voltage measurement at B-18 
cylinder 2, 3 oxygen sensor (rear) connector.

• Use special tool test harness (MD998464) to 

connect connector, and measure at pick-up 
harness.

• Transmission: Neutral <M/T> or P range <A/T>

• Engine: After warm-up

• Voltage between terminal No. 4 and earth.

OK:

When the engine is 2,500 r/min, the output 

voltage should repeat 0 to 0.8 V alternately.

Q: Is the check result normal?

YES : 

Go to Step 10 .

NO : 

Go to Step 8 .

AK300977

1

2

3

4

AC

Connector: B-18

Harness side 
connector

B-18 (B)

Cylinder 2, 3
oxygen sensor
(rear)

AK305616AB

Connector: C-113

<L.H. drive vehicles>

<R.H. drive vehicles>

C-113 (GR)

C-113 (GR)

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

Harness side connector

AK300977

1

2

3

4

AC

Connector: B-18

Harness side 
connector

B-18 (B)

Cylinder 2, 3
oxygen sensor
(rear)