Mitsubishi Evolution X. Manual - part 274

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-73

DTC P0032: Heated Oxygen Sensor (front) Heater Circuit High

AK704225

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HEATED OXYGEN SENSOR (FRONT) HEATER CIRCUIT

20A

WHITE

BLUE-BLA

CK

WHITE

WHITE

A-34X

MFI
RELAY

RELAY BOX
(ENGINE COMPARTMENT)

4

3

1

2

22

TO ECM

HEATED OXYGEN SENSOR
(FRONT)

1

4

2

3

TO ECM

TO ECM

ENGINE
CONTROL
MODULE

34

C-34

B-09

A-13

36

FUSIBLE LINK

BLUE

8

OFF

ON

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-74

.

CIRCUIT OPERATION

• Power is supplied from the MFI relay (terminal 

No. 2) to the heated oxygen sensor (front) heater.

• The ECM (terminal No. 34) controls continuity to 

the heated oxygen sensor (front) heater by turn-
ing the power transistor in the ECM "ON" and 
"OFF".

.

TECHNICAL DESCRIPTION

• The ECM checks whether the heater current is 

within a specified range when the heater is ener-
gized.

.

DESCRIPTIONS OF MONITOR METHODS

Heated oxygen sensor heater (front) current is out of 

specified range.

.

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)

• Not applicable

.

AK704229AB

Connector: A-13

A-13

AK704226

Connector: A-34X

MFI relay

A-34X

AB

AK704227

Connector: B-09

ECM

B-09 (GR)

AB

AK704228

AB

Heated oxygen
sensor (front)

Connector: C-34

C-34 (B)

SRS-ECU

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-75

DTC SET CONDITIONS
Logic Flow Chart

.

Check Conditions

• More than 2 seconds have passed since the 

engine starting sequence was completed.

• While the heated oxygen sensor (front) heater is 

on.

• Battery positive voltage is between 11 and 16.5 

volts.

Judgement Criterion

• The heated oxygen sensor (front) heater current 

has continued to be higher than 10.5 ampere for 
2 seconds.

.

FAIL-SAFE AND BACKUP FUNCTION

• None

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Pattern 2 

P.13A-9

.

.

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

• Heated oxygen sensor (front) heater failed.

• ECM failed.

End

No

No

Malfunction

Good

Current < 0.17A

or

Current > 10.5A

Voltage < 2.0V

AK604306

Heater ON

No

No

Start

Yes

Yes

Yes

Yes

Yes

No

Continuous
failure for 2secs

Monitoring
conditions

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-76

DIAGNOSIS

Required Special Tool:

• MB991658: Test Harness

STEP 1. Check the heated oxygen sensor (front).
(1) Disconnect heated oxygen sensor (front) connector C-34 

and connect test harness special tool, MB991658, to the 
connector on the heated oxygen sensor (front) side.

(2) Measure the resistance between heated oxygen sensor 

connector terminal No. 1 and terminal No. 2.

Standard value: 4.5 

− 8.0 Ω [at 20° C (68° F)]

Q: Is the measured resistance between 4.5 and 8.0 

Ω [at 

20

° C (68° F)]?

YES : Go to Step 2.
NO :  Replace the heated oxygen sensor (front). Then go to 

Step 3.

STEP 2. Check the trouble symptoms.
(1) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function 

− OBD-II Drive Cycle − Pattern 2 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0032 set?

YES : Replace the ECM. When the ECM is replaced, 

register the ID code. Refer to GROUP 42B, ID Code 
Registration Necessity Judgment Table <Vehicles 
with KOS> 

P.42B-12

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 3.

NO :  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 Malfunctions 

P.00-15

. 

STEP 3. 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 − Pattern 2 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0032 set?

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

AK604492AB

MB991658

Heated oxygen
sensor component
side connector