Mitsubishi Colt Ralliart. Manual - part 29

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-70

TROUBLE JUDGMENT

Check Conditions

• After engine starts <M/T>

• Engine coolant temperature is 20°C or higher.

• While oxygen sensor heater is on <CVT>.

• Engine speed is approximately 50 r/min or more 

<CVT>.

• Battery positive voltage is 11 − 16 V

Judgment Criterion

• Oxygen sensor heater currents has continued to 

be 0.16 A or lower, or 5 A or higher for 4 seconds.

PROBABLE CAUSES

• Failed oxygen sensor heater

• Open/short circuit in oxygen sensor heater circuit 

or loose connector contact

• Failed engine-ECU <M/T> or engine-CVT-ECU 

<CVT>

DIAGNOSIS PROCEDURE

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

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Repair or replace the connector.

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

• Disconnect connector, and measure at sensor 

side.

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

OK: 5 

− 30 Ω (at 20C°)

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Replace oxygen sensor.

STEP 3. Perform voltage measurement at A-122 
oxygen sensor 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 .

AK402012

2 1
4 3

Connector: A-122

A-122 (G)

AC

Oxygen sensor (front)

A-122 Harness side

connector

AK402012

2 1
4 3

Connector: A-122

A-122 (G)

AC

Oxygen sensor (front)

A-122 Harness side

connector

AK402012

2 1
4 3

Connector: A-122

A-122 (G)

AC

Oxygen sensor (front)

A-122 Harness side

connector

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-71

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

Q: Is the check result normal?

YES : 

Check intermediate connector A-17 and 

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

• Check power supply line for 

open/short circuit.

NO : 

Repair or replace the connector.

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

• Disconnect engine-ECU connector or 

engine-CVT-ECU connector, and connect special 
tool power plant ECU check harness 
(MB991987), and then 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 .

3

2

1

4

AK402060

B-106
J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

AK402012

2 1
4 3

Connector: A-122

A-122 (G)

AC

Oxygen sensor (front)

A-122 Harness side

connector

AK402745

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L

AE

A-114

Connector: 

A-114

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

Battery

A-114 Special tool power plant ECU check 
harness

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-72

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

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Repair or replace the connector.

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

• Check earthing line for open/short circuit.

Q: Is the check result normal?

YES : 

Replace engine-ECU <M/T> or 

engine-CVT-ECU <CVT>.

NO : 

Repair the damaged harness wire.

AK402745

6

4

2

5

3

1

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AD

A-114

Connector: 

A-114

Harness side connector

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

Battery

AK402012

2 1
4 3

Connector: A-122

A-122 (G)

AC

Oxygen sensor (front)

A-122 Harness side

connector

AK402745

6

4

2

5

3

1

9

7

8

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AD

A-114

Connector: 

A-114

Harness side connector

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

Battery

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-73

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

Q: Is the check result normal?

YES : 

Go to Step 9 .

NO : 

Repair or replace the connector.

STEP 9. Check harness between A-122 (terminal 
No. 3) oxygen sensor connector and B-106 
(terminal No. 4) engine control relay connector.

NOTE: Before checking harness, check intermediate 
connector A-17 and B-112, and repair if necessary.

• Check power supply line for damage.

Q: Is the check result normal?

YES : 

Go to Step 10 .

NO : 

Repair the damaged harness wire.

AK402745

6

4

2

5

3

1

9

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L

AD

A-114

Connector: 

A-114

Harness side connector

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

Battery

AK402012

2 1
4 3

Connector: A-122

A-122 (G)

AC

Oxygen sensor (front)

A-122 Harness side

connector

3

2

1

4

AK402060

B-106
J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

Main

Index

Group

TOC