Mitsubishi Galant (2004+). Manual - part 839

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-173

STEP 8. Using scan tool MB991958, read the diagnostic 
trouble code (DTC).

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK"(OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) After the DTC has been deleted, read the DTC again.
(4) Turn the ignition switch to the "LOCK"(OFF) position.
Q: Is DTC P0123 set?

YES : Retry the troubleshooting.
NO :  The inspection is complete.

AK303804AB

MB991910

DATA LINK
CONNECTOR

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-174

DTC P0125: Insufficient Coolant Temperature for Closed Loop Fuel Control

CAUTION

If DTC P0125 has been set, TCL related DTC 
U1120 is also set. After P0125 has been diag-
nosed, don't forget to erase DTC U1120.

1 2

52

51

53 54 55 56

57

58 59 60 61 62

63

64 65 66 67 68 69

70

71 72 73 74 75

76

77 78 79 80 81 82

83

100

99

92

91

93 94 95

96 97 98

101 102 103 104

105 106 107 108

109 110 111 112 113

AK303813

YELLO

W

-GREEN

BLA

CK

ENGINE COOLANT
TEMPERATURE SENSOR

POWERTRAIN CONTROL MODULE (PCM)

5 V

93

2

B-104

(MU802406)

69

1

Engine Coolant Temperature Sensor Circuit

B-21

B-22

AK303814

ENGINE
COOLANT
TEMPERATURE
SENSOR

AB

CONNECTOR: B-104

B-104 (B)

AK303013

CONNECTORS: B-21, B-22

PCM

AB

AIR CLEANER

B-22 (B)

B-21 (B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-175

.

CIRCUIT OPERATION

• 5-volt voltage is applied to the engine coolant 

temperature sensor output terminal (terminal No. 
1) from the PCM (terminal No. 93) via the resistor 
in the PCM. The ground terminal (terminal No. 2) 
is grounded with PCM (terminal No. 69).

• The engine coolant temperature sensor is a neg-

ative temperature coefficient type of resistor. It 
has the characteristic that when the engine cool-
ant temperature rises the resistance decreases.

• The engine coolant temperature sensor output 

voltage increases when the resistance increases 
and decreases when the resistance decreases.

.

TECHNICAL DESCRIPTION

• The engine coolant temperature sensor converts 

the engine coolant temperature to a voltage and 
outputs it.

• The PCM checks whether this voltage is within a 

specified range.

.

DESCRIPTIONS OF MONITOR METHODS

• Engine coolant temperature sensor output volt-

age drops from over 40

°C (104°F) to under 40°C 

(104

°F) and keeps under 40°C (104°F) for 5 min-

utes.

• Engine coolant temperature sensor output volt-

age does not reach close loop enable tempera-
ture within specified period when engine coolant 
temperature sensor output voltage at engine start 
is under 7

°C (45°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)

• Mass airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-176

DTC SET CONDITIONS <Range/Performance problem 

− drift>

Logic Flow Chart

.

Check Conditions, Judgement Criteria

• Engine coolant temperature decreases from 

higher than 40

°C (104°F) to lower than 40°C 

(104

°F).

• Then the engine coolant temperature has contin-

ued to be 40

°C (104°F) or lower for 5 minutes.

.

START

END

NO

NO

YES

YES

MALFUNCTION

GOOD

UNDER 40˚C (107˚F)

300secs HAVE PASSED?

NO

YES

OVER 40˚C (107˚F)

YES

OVER 40˚C (107˚F)

NO

AK302017