Mitsubishi Colt Ralliart. Manual - part 687

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-73

TROUBLE JUDGEMENT

Check Condition

• After engine starts

• Engine coolant temperature is more than 20°C.

• Battery voltage is more than 11 V and is less than 

16 V.

Judgement Criterion

• For 4 seconds, oxygen sensor (front) heater cur-

rent is less than 0.16 A or more than 5.0 A. 

PROBABLE CAUSES

• Failed oxygen sensor (front) heater

• Open/short circuit or damage in oxygen sensor 

heater circuit, or loose connector contact

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: A-122 oxygen sensor 
(front) connector

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Repair or replace.

STEP 2. Perform resistance measurement at 
A-122 oxygen sensor (front) connector.

• Disconnect connector and measure at sensor 

side.

• Resistance between terminals No. 3 and No. 4.

OK: 5 

− 30 Ω (at 20°C)

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Replace oxygen (front) sensor.

AK402087

Connector: A-122

Harness side 

connector

A-122(G)

AD

Oxygen sensor (front)

AK402087

Connector: A-122

Harness side 

connector

A-122(G)

AD

Oxygen sensor (front)

Main

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TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-74

STEP 3. Perform voltage measurement at A-122 
oxygen sensor (front) connector.

• Disconnect connector and measure at harness 

side.

• Ignition switch: ON

• Voltage between terminal No. 3 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 5 .

NO : 

Go to Step 4 .

STEP 4. Connector check: B-106 engine control 
relay connector

AK402087

Connector: A-122

Harness side 

connector

A-122(G)

AD

Oxygen sensor (front)

3

2

1

4

AK402084

J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

AK402087

Connector: A-122

Harness side 

connector

A-122(G)

AD

Oxygen sensor (front)

Main

Index

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TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-75

Q: Is the check result normal?

YES : 

Check intermediate connector A-17 and 

B-112, and repair if necessary. If 
intermediate connectors are normal, check 
and repair harness between A-122 (terminal 
No. 3) oxygen sensor (front) connector and 
B-106 (terminal No. 4) engine control relay 
connector.

• Check power supply line for 

open/short circuit.

NO : 

Repair or replace.

STEP 5. Perform voltage measurement at A-114 
engine-ECU connector.

• Disconnect engine-ECU connector, and connect 

special tool power plant ECU check harness 
(MB991987) and measure the voltage on the 
check connector.

• Ignition switch: ON

• Voltage between terminal No. 51 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 8 .

NO : 

Go to Step 6 .

STEP 6. Connector check: A-114 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Repair or replace.

AK402745

6

4

2

5

3

1

9

7

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10

11

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L

AF

A-114

Connector: 

A-114

Harness side connector

Engine-ECU

Battery

AK402745

6

4

2

5

3

1

9

7

8

10

11

12

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L

AF

A-114

Connector: 

A-114

Harness side connector

Engine-ECU

Battery

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-76

STEP 7. Check harness between A-122 (terminal 
No. 4) oxygen sensor (front) connector and A-114 
(terminal No. 51) engine-ECU connector.

• Check earthing line for open/short circuit.

Q: Is the check result normal?

YES : 

Replace engine-ECU.

NO : 

Repair.

STEP 8. Connector check: A-114 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 9 .

NO : 

Repair or replace.

AK402087

Connector: A-122

Harness side 

connector

A-122(G)

AD

Oxygen sensor (front)

AK402745

6

4

2

5

3

1

9

7

8

10

11

12

13

14

15

16

17

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51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

L

AF

A-114

Connector: 

A-114

Harness side connector

Engine-ECU

Battery

AK402745

6

4

2

5

3

1

9

7

8

10

11

12

13

14

15

16

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51

52

53

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61

62

63

64

65

66

L

AF

A-114

Connector: 

A-114

Harness side connector

Engine-ECU

Battery

Main

Index

Group

TOC