Mitsubishi Montero (2002-2004). Manual - part 696

TSB Revision

DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-481

STEP 14. Using scan tool MB991502, check data list item 
73: Fuel Tank Differential Pressure Sensor.

CAUTION

To prevent damage to scan tool MB991502, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.

(2) Disconnect hose F from the evaporative emission canister 

side, and plug the hose.

(3) Turn the ignition switch to the "ON" position.
(4) Remove the fuel cap.
(5) Set scan tool MB991502 to the data reading mode for item 

73, Fuel Tank Differential Pressure Sensor.

• The fuel tank pressures reading on the scan tool should 

be 

−3.3 to 3.3 kPa (−0.97 to 0.97 inHg).

(6) Connect an evaporative emission system pressure pump to 

the fuel tank filler tube and pressurize the fuel tank.

• The fuel tank pressure reading should increase.

(7) Disconnect an evaporative emission system pressure pump 

and connect hose F.

(8) Turn the ignition switch to the "LOCK" (OFF) position and 

disconnect scan tool MB991502.

Q: Is the fuel tank pressure between 

−3.3 and 3.3 kPa (−

0.97 and 0.97 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 15.

NO :  Replace the PCM. Go to Step 15.

STEP 15. Perform the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. [Refer to 

GROUP 13A, Trouble Code Diagnosis 

− OBD-II Drive Cycle 

(Procedure 1: Evaporative Emission Control system Leak 
Monitor) 

P.13Ab-2

].

(2) Read the diagnostic trouble code (DTC).
Q: Is DTC P0453 set?

YES : Go to Step 2.
NO :  The procedure is complete.

ACX01539

16-PIN

MB991502

AC

AC102602 AC

HOSE F

ACX01358

TSB Revision

DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-482

DTC P0455: Evaporative Emission System Leak Detected (Gross Leak)

.

AC203991

SYSTEM DIAGRAM

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

Q

S

R

P

FUEL TANK

CHECK VALVE B

CHECK VALVE A

EVAPORATIVE
EMISSION
PURGE
SOLENOID

EVAPORATIVE EMISSION
VENTILATION SOLENOID

EVAPORATIVE
EMISSION
CANISTER

OVER VENT
VALVE MODULE

VENT PIPE
ASSEMBLY

AB

AC101766

EVAPORATIVE EMISSION CANISTER

AB

AC203904

AC

EVAPORATIVE EMISSION
PURGE SOLENOID

INTAKE AIR DUCT

AC101763 AB

REAR COIL SPRING (RH)

EVAPORATIVE EMISSION VENTILATION 
SOLENOID

TSB Revision

DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-483

TECHNICAL DESCRIPTION

• The fuel tank may be under a slight positive and 

negative pressure depending on the state of the 
evaporative emission system. The PCM monitors 
and responds to these pressure changes. If the 
pressure varies from the specified range, the 
PCM will set DTC P0455.

• The PCM energizes the evaporative emission 

ventilation solenoid to shut off the evaporative 
emission canister outlet port.

• The evaporative emission purge solenoid is to 

apply engine manifold vacuum to the evaporative 
emission system.

• When the fuel system develops a vacuum of 2 

kPa (0.29 psi), the evaporative emission purge 
solenoid is turned "OFF" and the fuel system vac-
uum is maintained at 2 kPa (0.29 psi).

• The PCM determines if there is a leak or clog in 

the fuel system by measuring the change of vac-
uum inside the fuel tank.

• The test is stopped when fuel vapor pressure is 

determined to be too high.

.

DTC SET CONDITIONS

Test Conditions:

• Engine coolant temperature is less than 36°C 

(97

°F) when the engine is started.

• Intake air temperature is less than 36°C (97°F) 

when the engine is started.

• Engine coolant temperature is greater than 60°C 

(140

°F) When the amount of remaining fuel is 15 

− 40 percent of capacity upon engine start up.

• Engine coolant temperature is greater than 20°C 

(68

°F) when the amount of remaining fuel is 40 − 

85 percent of capacity upon engine start up.

• Intake air temperature is greater than 5°C (41°F).

• Fuel tank temperature is less than 36°C (97°F).

• Barometric pressure is greater than 76 kPa (11 

psi).

• Volumetric efficiency is between 20 and 70 per-

cent.

• Fuel tank differential pressure sensor output volt-

age is 1 

− 4 volts.

• When the evaporative emission purge solenoid 

and evaporative emission ventilation solenoid are 
closed, the pressure in the fuel tank rises to 451 
Pa (0.065 psi) or less and the amount of remain-
ing fuel is 15 

− 40 percent of capacity upon 

engine start up.

• When the evaporative emission purge solenoid 

and evaporative emission ventilation solenoid are 
closed, the pressure in the fuel tank rises to 324 
Pa (0.047 psi) or less and the amount of remain-
ing fuel is 40 

− 85 percent of capacity upon 

engine start up.

• Engine speed is greater than 1,600 r/min.

• 10 seconds have elapsed from the start of the 

previous monitoring.

• Monitoring time: 150 seconds.

Judgment Criteria:

• The fuel tank internal pressure is greater than 2 

kPa (0.29 psi) after the evaporative emission 
purge solenoid has been driven when the fuel 
tank and vapor line were closed.

.

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

• Loose fuel cap.

• Fuel cap relief pressure is incorrect.

• Malfunction of the fuel overflow limiter valve.

• Purge line or vapor line is clogged.

• Malfunction of the fuel tank, purge line or vapor 

line seal.

• Malfunction of the evaporative emission purge 

solenoid.

• Malfunction of the evaporative emission ventila-

tion solenoid.

• Malfunction of the fuel tank differential pressure 

sensor.

• Malfunction of the evaporative emission canister 

seal.

• Evaporative emission canister is clogged.

.

OVERVIEW OF TROUBLESHOOTING

• To determine the cause of DTC P0455, a perfor-

mance test is needed. The performance test uses 
a mechanical vacuum gauge and scan tool 
MB991502 set to data reading mode for the fuel 
tank differential pressure sensor (TANK PRES 
SNER 73). The mechanical gauge reading is 
used to verify the scan tool reading. A compari-
son of the mechanical gauge and scan tool 
MB991502 determines whether there is a prob-
lem in the system

• Prior to doing the performance test, ensure that 

the fuel cap is closed securely. Inspect all EVAP 
system hoses and tubes for damage.

TSB Revision

DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-484

DIAGNOSIS

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

STEP 1. Using scan tool MB991502, check evaporative 
emission system monitor test.

CAUTION

• To prevent damage to scan tool MB991502, always turn 

the ignition switch to the "LOCK" (OFF) position before 
connecting or disconnecting scan tool MB991502.

• During this test, the PCM automatically increases the 

engine speed to 1,600 r/min or greater. Check that the 
transmission is set to "P" position.

(1) Connect scan tool MB991502 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Erase the DTCs using scan tool MB991502. (Refer to 

GROUP 13A, Trouble Code Diagnosis 

P.13Ab-2

).

(4) Check that the fuel cap is securely closed. (Tighten until 

three clicks are heard).

(5) Start the engine.
(6) Select "System Test" and press the "YES" key.
(7) Select "Evap Leak Mon" and press the "YES" key.
(8) During this test, keep the accelerator pedal at the idling 

position.

(9) Keep the engine speed and engine load within the specified 

range. When the monitor test starts, the "In Progress" item 
on scan tool MB991502 will change from "NO" to "YES".

(10)Turn the ignition switch to the "LOCK" (OFF) position and 

disconnect scan tool MB991502.

Q: What is displayed on scan tool MB991502?

"Evap Leak Mon. Completed Test Passed" : The EVAP 

system is working properly at this time. Explain to the 
customer that an improperly tightened fuel cap can 
cause MIL to turn on. Return the vehicle to the 
customer.

"Evap Leak Mon. Completed. Test Failed and DTCs Set" 
: 

A malfunction has been detected during the monitor 
test. Refer to GROUP 13A, Diagnostic Trouble Code 
Chart 

P.13Ab-22

, and diagnose any other DTCs that 

are set. If no other DTCs have been set, go to Step 2.

"Evap Lead Mon. Discontinued. Retest again from the 
first" : The EVAP monitor was interrupted during the test. 

Turn the ignition switch to the "LOCK" (OFF) position 
once, and repeat the monitoring from Step 1.

ACX01543

MB991502

AB

16-PIN