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Mitsubishi Eclipse. Manual - part 185

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-233

DTC P0131: Heated Oxygen Sensor Circuit Low Voltage (sensor 1)

AK000657

1 2
3

ACK

WHITE

B-17
MU802605

ENGINE CONTROL
MODULE (ECM) <M/T>
OR
POWERTRAIN CONTROL
MODULE (PCM) <A/T>

HEATED OXYGEN
SENSOR (FRONT)

FROM MFI RELAY

TO ECM
OR PCM

92 <M/T>
57 <A/T>*1

76 <M/T>
71 <A/T>*2

C-60 <M/T>
(MU803772)

C-54 <A/T>
(MU803781)

C-57 <A/T>
(MU803782)

NOTE
*1:PCM connector C-54 <A/T>
*2:PCM connector C-57 <A/T>

88 89

76 77

72
79
91

73
80

81
92

8283
93

8485

8687

9596

89 90 91 92

83 84

42 43
48 49 50 51 52 53 54 55 56 57

58 59

60 61 62 63

64 65 66

Heated Oxygen Sensor (front) Circuit

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L>

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CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the ECM (ter-
minal No. 76) <M/T> or PCM (terminal No. 71)
<A/T> from the output terminal (terminal No. 4) of
the heated oxygen sensor (front).

• Terminal No. 2 of the heated oxygen sensor

(front) is grounded with ECM (terminal No. 92)
<M/T> or PCM (terminal No. 57) <A/T>.

TECHNICAL DESCRIPTION

• The heated oxygen sensor (front) detects the

concentration of oxygen in the exhaust gas; it
converts those data to voltage, and inputs the
resulting signals to the ECM <M/T> or PCM
<A/T>.

• When the heated oxygen sensor (front) begins to

deteriorate, the heated oxygen sensor signal
response becomes poor.

• The ECM <M/T> or PCM <A/T> forcibly varies

the air/fuel mixture to make it leaner and richer,
and checks the response speed of the heated
oxygen sensor (front). In addition, the ECM
<M/T> or PCM <A/T> also checks for an open
circuit in the heated oxygen sensor (front) output
line.

DESCRIPTIONS OF MONITOR METHODS
Heated oxygen sensor (front) output voltage stays

low when air/fuel ratio is forced to be rich. The
above procedure is repeated when oxygen sen-
sor is inactive.

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 heater (front) monitor

• Misfire monitor

• Fuel system monitor

Sensor (The sensor below is determined to be

normal)

• Volume airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

AK300051AB

B-17 (B)

HEATED OXYGEN
SENSOR (FRONT)

CONNECTOR: B-17

AK300060

ECM

CONNECTOR: C-60 <M/T>

C-60 (G)

AK300060

PCM

CONNECTORS: C-54, C-57 <A/T>

C-57 (GR)

C-54 (GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-235

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

• 3 minutes or more have passed since the starting

sequence was completed.

• Heated oxygen sensor (front) signal voltage has

continued to be 0.2 volt or lower.

• Engine coolant temperature is higher than 76°C

(169

°F).

• Engine speed is higher than 1,200 r/min.

• Volumetric efficiency is higher than 25 percent.

• Volume airflow sensor output frequency is 75 Hz

or more.

START

> =4.5V

2secs HAS PASSED

YES

MALFUNCTION

MONITORING

CONDITIONS

YES

MONITORING

CONDITIONS

+5V ON

AK301436

< 0.2V

10secs HAS PASSED

YES

END

MALFUNCTION

GOOD

MODULATE A/F CONDITION TO RICH

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L>

13A-236

• At least 20 seconds have passed since fuel shut

off control was canceled.

• Monitoring time: 10 seconds.

Judgement Criteria

• Making the air/fuel ratio 15 percent for 10 sec-

onds richer does not result in raising the heated
oxygen sensor (front) output voltage beyond 0.2
volt.

OBD-ll DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-ll Drive Cycle −

Procedure 6

− Other Monitor

P.13A-5

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

• Heated oxygen sensor (front) deteriorated.

• Short circuit in heated oxygen sensor (front) out-

put line.

• Connector damage.

• ECM failed. <M/T>

• PCM failed. <A/T>

DIAGNOSIS

Required Special Tools:

• MD998464: Test Harness

STEP 1. Using scan tool MB991958, check data list item 11:
Heated Oxygen Sensor (front).

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

11, Heated Oxygen Sensor (front).

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

output voltage should be 0.6 to 1.0 volt.

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

output voltage should repeat 0.4 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 : It can be assumed that this malfunction is intermittent.

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

P.00-6

NO : Go to Step 2.

AK300810

MB991911

16-PIN

MB991827

MB991824

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