Mitsubishi Colt Ralliart. Manual - part 686

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-69

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

Q: Is the check result normal?

YES : 

Check and repair harness between A-122 

(terminal No. 2) oxygen sensor (front) 
connector and A-114 (terminal No.49) 
engine-ECU connector.

• Check earthing line for damage.

NO : 

Repair or replace.

STEP 9. Perform voltage measurement at A-122 
oxygen sensor (front) connector.

• Use special tool test harness (MB991658) to con-

nect connector, and measure at pick-up harness.

• Transmission: P range

• Engine: Idling after warm-up

• Voltage between terminal No. 1 and earth.

OK:

When the engine is idling and running at 2,500 

r/min, the output voltage repeats changing 
between 0 and 0.8 V.

When the engine is rapidly decelerated from 

4,000 r/min, the output voltage below 200 mV 
increases to between 600 and 1,000 mV after 
a lapse of a few seconds.

Q: Is the check result normal?

YES : 

Go to Step 12 .

NO : 

Go to Step 10 .

STEP 10. Check oxygen sensor (front) itself.

• Check oxygen sensor (front) itself (Refer to 

P.13B-365

).

Q: Is the check result normal?

YES : 

Go to Step 11 .

NO : 

Replace oxygen sensor.

AK402745

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AF

A-114

Connector: 

A-114

Harness side connector

Engine-ECU

Battery

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

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-70

STEP 11. Connector check: A-114 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Check and repair harness between A-122 

(terminal No. 1) oxygen sensor (front) 
connector and A-114 (terminal No. 34) 
engine-ECU connector.

• Check output line for damage.

NO : 

Repair or replace.

STEP 12. Perform voltage measurement at A-114 
engine-ECU connector.

• Disconnect connector, connect special tool power 

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

• Transmission: Neutral

• Engine: Idling after warm-up

• Voltage between terminal No. 34 and earth.

OK:

When the engine is idling and running at 2,500 

r/min, the output voltage repeats changing 
between 0 and 0.8 V.

When the engine is rapidly decelerated from 

4,000 r/min, the output voltage below 200 mV 
increases to between 600 and 1,000 mV after 
a lapse of a few seconds.

Q: Is the check result normal?

YES : 

Go to Step 14 .

NO : 

Go to Step 13 .

AK402745

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L

AF

A-114

Connector: 

A-114

Harness side connector

Engine-ECU

Battery

AK402087

Connector: A-122

Harness side 

connector

A-122(G)

AD

Oxygen sensor (front)

AK402745

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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-71

STEP 13. Connector check: A-114 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Check and repair harness between A-122 

(terminal No. 1) oxygen sensor (front) 
connector and A-114 (terminal No. 34) 
engine-ECU connector.

• Check output line for open circuit.

NO : 

Repair or replace.

STEP 14. Connector check: A-114 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Repair or replace.

AK402745

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L

AF

A-114

Connector: 

A-114

Harness side connector

Engine-ECU

Battery

AK402087

Connector: A-122

Harness side 

connector

A-122(G)

AD

Oxygen sensor (front)

AK402745

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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-72

Code No. P0135: Oxygen Sensor (front) Heater System

OPERATION

• Power is supplied to the heater power terminal 

(terminal No. 3) of the oxygen sensor (front) con-
nector from the engine control relay (terminal No. 
4).

• The heater (terminal No. 4) of the oxygen sensor 

(front) connector is controlled by the power tran-
sistor in the engine-ECU (terminal No. 51).

FUNCTION

• Power supply to the oxygen sensor (front) heater 

is controlled through ON-OFF control of the 
power transistor in the engine-ECU.

• The oxygen sensor (front) heater helps the oxy-

gen sensor be highly responsive particularly 
when the exhaust emission temperature is low.

AK402681

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1213

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8 9

L

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37
52 53 54 555657585960616263646566

38 39 404142434445464748495051

22 23 24 252627282930313233343536

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Oxygen sensor (front)

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51

Engine
control
relay

R

LG-R

R

Fusible link

B-106

A-114

B-112

B-108

A-122

MU802083

Oxygen Sensor Heater (front) Circuit

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  P: Purple

16

20A

J/B

AE

Engine-ECU

To engine-ECU

To engine-ECU

A-17

4

R

Main

Index

Group

TOC