Mitsubishi Galant (2004+). Manual - part 1236

 

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Mitsubishi Galant (2004+). Manual - part 1236

 

 

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-637

STEP 11. Check for harness damage between EGR valve 
connector B-07 and PCM connector B-23.

a. EGR valve connector B-105 (terminal No. 1) and PCM con-

nector B-23 (terminal No. 142). 

b. EGR valve connector B-105 (terminal No. 3) and PCM con-

nector B-23 (terminal No. 136).

c. EGR valve connector B-105 (terminal No. 4) and PCM con-

nector B-23 (terminal No. 130).

d. EGR valver connector B-105 (terminal No. 6) and PCM con-

nector B-23 (terminal No. 124).

Q: Is the harness wire in good condition?

YES : Replace the PCM. Then go to Step 12.
NO :  Repair it. Then go to Step 12.

STEP 12. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function 

− OBD-II Drive Cycle − Procedure 6 − 

Other Monitor 

P.13B-5

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0403 set?

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

1

2 3

4

5 6

AK303137AB

B-105(GR)

CONNECTOR: B-105

EGR 
VALVE

BRAKE FLUID
RESERVOIR

HARNESS 
CONNECTOR: 
COMPONENT SIDE

127 126 125 124 123 122 121

133 132 131 130 129 128

140 139 138 137 136 135 134

146 145 144 143 142 141

153 152 151 150 149 148 147

AK303058

HARNESS CONNECTOR: 
COMPONENT SIDE

CONNECTOR: B-23

B-23

PCM

AB

AIR CLEANER

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-638

DTC P0421: Warm up catalyst Efficiency Below Threshold (bank 1)

.

TECHNICAL DESCRIPTION

• The signal from the rear heated oxygen sensor 

differs from the front heated oxygen sensor. That 
is because the catalytic converter purifies 
exhaust gas. When the catalytic converter has 
deteriorated, the signal from the front heated oxy-
gen sensor becomes similar to the rear heated 
oxygen sensor.

• The PCM compares the output of the front and 

rear heated oxygen sensor signals.

.

DESCRIPTIONS OF MONITOR METHODS
Front and rear heated oxygen sensor rich/lean 

switching frequencies are nearly equal.

.

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)

• Heated oxygen sensor (front) monitor

• Heated oxygen sensor (rear) monitor

• Heated oxygen sensor heater (front) monitor

• Heated oxygen sensor heater (rear) monitor

• Misfire monitor

• Fuel system monitor

• Air/fuel ratio feedback monitor

• Oxygen sensor heater (front)

• Oxygen sensor heater (rear)

Sensor (The sensor below is determined to be 

normal)

• Mass airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

• Accelerator pedal position sensor

.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-639

DTC SET CONDITIONS

Logic Flow Chart

.

Check Conditions

• Engine speed is lower than 3,000 r/min.

• Accelerator pedal is open.

• Mass airflow is between 9 and 30 g/sec.

• More than 3 seconds have elapsed after the 

above-mentioned three conditions have been 
met.

• Intake air temperature is higher than −10°C 

(14

°F).

• Barometric pressure is higher than 76 kPa (22.4 

in.Hg).

• Under the closed loop air/fuel ratio control.

• Vehicle speed is 1.5 km/h (1.0 mph) or more.

• The PCM monitors for this condition for 7 cycles 

of 12 seconds each during the drive cycle.

• Short-term fuel trim is higher than −30 percent 

and lower than +25 percent.

• The cumulative mass airflow is higher than 1,638 

g.

Judgment Criteria

• When the monitoring for 12 seconds is carried 

out 7 times, the frequency ratio of rear and front 
is 0.8 or more.

.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Procedure 3 

− Catalytic Converter Monitor 

P.13B-5

.

.

TROUBLESHOOTING HINTS (The most likely 
causes for this code to be set are: )

• Right bank side catalytic converter deteriorated.

• Right bank heated oxygen sensor failed.

• Exhaust leak.

• PCM failed.

START

MONITORING

CONDITIONS

Rf > R0

MALFUNCTION

GOOD

END

NO

NO

YES

YES

CALCULATE AVERAGE FREQUENCY

RATIO (Rf = Fr/Ff) OF SPECIFIED TIMES

R0: AVERAGE THRESHOLD VALUE.

AK303028

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-640

DIAGNOSIS

Required Special Tools:

• MB991958: Scan tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

STEP 1. Check for exhaust leak.
Q: Are there any abnormalities?

YES : Repair it. Then go to Step 7.
NO :  Go to Step 2.

STEP 2. Using scan tool MB991958, check data list item 69: 
Heated Oxygen Sensor Bank 1, Sensor 2 (right rear).

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) Start the engine and run at idle.

(3) Set scan tool MB991958 to the data reading mode for item 

69, Heated Oxygen Sensor Bank 1, Sensor 2 (right rear).

• Warming up the engine. When the engine is revved, the 

output voltage should repeat 0 volt and 0.6 to 1.0 volt 
alternately.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : Go to Step 3.
NO :  Refer to DTC P0136 

− Heated Oxygen Sensor Circuit 

(Bank 1, Sensor 2) 

P.13B-250

, DTC P0137 

− Heated 

Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor 
2) 

P.13B-268

, DTC P0138 

− Heated Oxygen Sensor 

Circuit High Voltage (Bank 1, Sensor 2) 

P.13B-275

DTC P0139 

− Heated Oxygen Sensor Circuit Slow 

Response (Bank 1, Sensor 2) 

P.13B-280

.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

 

 

 

 

 

 

 

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