Mitsubishi Grandis. Manual — part 733

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-183

Code No. P0431: Warm Up Catalyst Malfunction (Cylinder 2, 3)

FUNCTION

• The signal from the cylinder 2, 3 oxygen sensor

(rear) differs from the cylinder 2, 3 oxygen sensor
(front). That is because the catalytic converter
purifies exhaust gas. When the catalytic
converter has deteriorated, the signal from the
cylinder 2, 3 oxygen sensor (front) becomes
similar to the cylinder 2, 3 oxygen sensor (rear).

• The engine-ECU <M/T> or engine-A/T-ECU

<A/T> compares the output of the cylinder 2, 3
oxygen sensor signals (front and rear).

TROUBLE JUDGMENT

Check Conditions

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

• The accelerator pedal is open.

• Air flow sensor output is 8 gm/s or higher.

• 3 seconds or more elapsed after the

abovementioned conditions were satisfied.

• Intake air temperature is −10°C or higher after the

engine is started.

• Barometric pressure is 76 kPa or higher.

• Under the closed loop air/fuel ratio control.

• Vehicle speed is 1.5 km/h or higher.

• For 10 seconds per cycle, the engine-ECU

<M/T> engine-A/T-ECU <A/T> monitors 7 cycles
of this condition during the drive cycle.

• Short-term fuel trim is between −25 % or higher

and +25 % or lower.

• The cumulative air flow sensor output is 2,931 g

or higher.

Judgment Criterion

• The cylinder 2, 3 oxygen sensor (rear) signal

frequency divided by cylinder 2, 3 oxygen sensor
(front) signal frequency is 0.8 or more.

PROBABLE CAUSE

• Catalytic converter deteriorated

• Failed cylinder 2, 3 oxygen sensor (front)

• Failed cylinder 2, 3 oxygen sensor (rear)

• Failed engine-ECU <M/T>

• Failed engine-A/T-ECU <A/T>

DIAGNOSIS PROCEDURE

STEP 1. Check for leakage of exhaust emission
from exhaust manifold.

Q: Is the check result normal?

YES :

Go to Step 2 .

NO :

Repair.

STEP 2. MUT-III data list

• Refer to Data List Reference Table

P.13A-363

.

a. Item 39: Cylinder 2, 3 oxygen sensor (front)
b. Item 69: Cylinder 2, 3 oxygen sensor (rear)

Q: Are the check results normal?

YES :

Go to Step 3 .

NO :

Perform the diagnosis code classified check
procedure for the sensor that has shown an
abnormal data valve (Refer to Inspection
Chart for Diagnosis Code

P.13A-20

).

STEP 3. MUT-III data list

• Item 39: Cylinder 2, 3 oxygen sensor (front)

OK: 0

− 0.4 and 0.6 − 1.0 volt should alternate

15 times or more within 10 seconds (engine
speed at 2,000 r/min).

Q: Is the check result normal?

YES :

Go to Step 4 .

NO :

Replace the cylinder 2, 3 oxygen sensor
(front).

STEP 4. Replace the cylinder 2, 3 oxygen sensor
(rear).

• After replacing the cylinder 2, 3 oxygen sensor

(rear), re-check the trouble symptoms.

Q: Is the check result normal?

YES :

Check end.

NO :

Go to Step 5 .

STEP 5. Replace the catalytic converter (cylinder
2, 3).

• After replacing the catalytic converter (cylinder 2,

3), re-check the trouble symptoms.

Q: Is the check result normal?

YES :

Replacing engine-ECU <M/T> or

engine-A/T-ECU <A/T>.

NO :

Check end.

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-184

Code No. P0443: Purge Control Solenoid Valve System

OPERATION

• Power is supplied to the purge control solenoid

valve (terminal No. 2) from the engine control
relay (terminal No. 1).

• The engine-ECU <M/T> or engine-A/T-ECU

<A/T> (terminal No. 23) makes the power
transistor in the unit be in ON position, and that
makes currents go on the purge control solenoid
valve (terminal No. 1).

2

1

1

2

3

4

1

2

3

5

6 7 8 9

4

20

21 22

232425

2627

10111213

14 15

16 1718

19

AK305564

Engine
control
relay

B-15X

1

2

23

Engine-ECU <M/T> on
engine-A/T-ECU <A/T>

B-01
MU802779

Purge
control
solenoid
valve

1

2

Purge control solenoid valve circuit

W-G

BR

W-G

Battery

4

3

C-110

(MU803802)

AB

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

11

2

J/C(4)

C-116

R-W

R-W

To engine-ECU <M/T> or
engine-A/T-ECU <A/T>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-185

FUNCTION

• In response to a signal from the engine-ECU

<M/T> or engine-A/T-ECU <A/T>, the purge
control solenoid valve controls the flow rate of the
purge air to be introduced into the surge tank.

TROUBLE JUDGMENT

Check Conditions

• Ignition switch is in ON position.

• Battery positive voltage is 10 V or higher.

Judgment Criterion

• The surge voltage (system voltage +2 V) of

solenoid coil is not detected when the purge
control solenoid valve is turned in OFF position
from ON.

PROBABLE CAUSE

• Failed purge control solenoid valve

• Open/short circuit in purge control solenoid value

circuit or loose connector contact

• Failed engine-ECU <M/T>

• Failed engine-A/T-ECU <A/T>

DIAGNOSIS PROCEDURE

STEP 1. MUT-III actuator test

• Item 08: Purge control solenoid valve

OK: Operating sound can be heard and the
valve vibrates

Q: Is the check result normal?

YES :

Intermittent malfunction (Refer to GROUP

00

− How to Use

Troubleshooting/Inspection Service Points

P.00-5

).

NO :

Go to Step 2 .

STEP 2. Connector check: B-01 purge control
solenoid valve connector

Q: Is the check result normal?

YES :

Go to Step 3 .

NO :

Repair or replace.

STEP 3: Perform resistance measurement at B-01
purge control solenoid valve connector.

• Disconnect connector, and measure at solenoid

valve side.

• Resistance between terminal No. 1 and No. 2.

OK: 30

− 34 Ω (at 20°C)

Q: Is the check result normal?

YES :

Go to Step 4 .

NO :

Replace purge control solenoid valve.

STEP 4. Perform voltage measurement at B-01
purge control solenoid valve connector.

• Disconnect connector, and measure at harness

side.

• Ignition switch: ON

• Voltage between terminal No. 2 and earth.

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 6 .

NO :

Go to Step 5 .

AK305619

1

2

AB

Connector: B-01

B-01(B)

Harness
side connector

AK305619

1

2

AB

Connector: B-01

B-01(B)

Harness
side connector

AK305619

1

2

AB

Connector: B-01

B-01(B)

Harness
side connector

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-186

STEP 5. Connector check: B-15X engine control
relay connector

Q: Is the check result normal?

YES :

Check intermediate connector C-116, and

repair if necessary. If intermediate
connector is normal, check and repair
harness between B-01 (terminal No. 2)
purge control solenoid valve connector and
B-15X (terminal No. 1) engine control relay
connector.

• Check power line for open/short

circuit.

NO :

Repair or replace.

STEP 6. Perform voltage measurement at C-110
engine-ECU <M/T> connector or engine-A/T-ECU
<A/T> connector.

• Disconnect connector, and measure at harness

side.

• Ignition switch: ON

• Voltage between terminal No. 23 and earth.

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 8 .

NO :

Go to Step 7 .

AK300967

2

1

3

4

AC

Harness side
connector

B-15X

Connector: B-15X

Relay box’s
triangle marks

AK305619

1

2

AB

Connector: B-01

B-01(B)

Harness
side connector

AK305618AB

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

Connector: C-110

<L.H. drive vehicles>

<R.H. drive vehicles>

C-110 (GR)

C-110 (GR)

Harness side connector