Mitsubishi Galant (2004+). Manual - part 1254

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-709

STEP 14. Check the harness wires between PCM 
connector B-20 terminal 22 and fuel tank differential 
pressure sensor connector D-23 terminal 2 for damage.

Q: Are the harness wires in good condition?

YES : Go to Step 17.
NO :  Repair the damaged harness wires. Then go to Step 

17.

STEP 15. Check fuel tank differential pressure sensor 
connector D-23 for loose, corroded or damaged terminals, 
or terminals pushed back in the connector.

Q: Is the connectors and terminals in good condition?

YES : Replace the fuel tank differential pressure sensor. 

Then go to Step 17.

NO :  Repair or replace the faulty components (Refer to 

GROUP 00E, Harness Connector Inspection 

P.00E-2

). Then go to Step 17.

AC306248

B-20 HARNESS

CONNECTOR:

COMPONENT SIDE

AB

B-20

CONNECTOR: B-20

PCM

AIR
CLEANER

AC305266

CONNECTOR: D-23

AB

D-23 (B)

AC305266

CONNECTOR: D-23

AB

D-23 (B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-710

STEP 16. Using scan tool MB991958, check data list item 
73: Fuel Tank Differential Pressure Sensor.

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) Disconnect hose H from the evaporative emission canister, 

and plug the hose.

(3) Turn the ignition switch to the "ON" position.
(4) Remove the fuel cap.
(5) Set scan tool MB991958 to the data reading mode.

• Item 73, Fuel Tank Differential Pressure Sensor.

• The fuel tank pressure reading on the scan tool 

should be 

−1.5 to 1.5 kPa (−0.443 to 0.443 inHg).

(6) Connect the evaporative emission system pressure pump 

(Miller number 6872A) to the fuel tank filler tube by using 

fuel tank adapter (MLR-8382) and pressurize the fuel tank.

• The fuel tank pressure reading should increase.

(7) Turn the ignition switch to the "LOCK" (OFF) position. Then 

disconnect scan tool MB991958.

(8) Remove  the evaporative emission system pressure pump 

(Miller number 6872A) and the fuel tank adapter 
(MLR-8382), and reinstall the fuel cap.

(9) Connect hose H to the evaporative emission canister.
Q: Is the fuel tank pressure between 

−1.5 and 1.5 kPa 

(

−0.443 and 0.443 inHg)?

YES : It can be assumed that this malfunction is intermittent 

(Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunction 

P.00-6

). Go to 

Step 17.

NO :  Replace the PCM (Refer to 

P.13B-1146

). Then go to 

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC306778

AC

HOSE H

PLUG

AC306661

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-711

Step 17   .

STEP 17. Perform the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern (Refer to 

Diagnostic Function 

− OBD-ll Drive Cycle − Procedure 1 − 

Evaporative Emission System Leak Monitor 

P.13B-5

).

(2) Read the diagnostic trouble code (DTC).
Q: Is DTC P0451 set?

YES : Repeat the troubleshooting from Step 2.
NO :  The procedure is complete.

CONTINUE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-712

13B

DTC P0452: Evaporative Emission System Pressure Sensor Low Input

AC306278

A

B

C

D

E

F

G

O

P

Q

N

M

L

H

I

J

K

AC

INTAKE MANIFOLD PLENUM

FUEL TANK

EVAPORATIVE EMISSION
VENTILATION SOLENOID

CHECK VALVE

EVAPORATIVE EMISSION
PURGE SOLENOID

EVAPORATIVE 
EMISSION CANISTER

ONBOARD REFUELING
VAPOR RECOVERY(ORVR)
VENT VALVE MODULE

FUEL TANK DIFFERENTIAL 
PRESSURE SENSOR

SYSTEM DIAGRAM

CHAMBER

FUEL TANK 
DIFFERENTIAL 
PRESSURE 
SENSOR

POWERTRAIN 
CONTROL 
MODULE

Fuel Tank Differential Pressure Sensor Circuit

AC306128