Mitsubishi Montero (2002-2004). Manual - part 576

13Ac-1

GROUP 13Ac

TSB Revision

DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-2

.

DTC P0101: Volume Airflow Circuit Range/Performance Ploblem

1 2 3 4 5 6 7

3 4

1 2

RED

GREEN

WHITE-BLA

CK

SKY B

ULE

WHITE-

BLA

CK

WHITE-

BLA

CK

AK201126

B-48

B-22X

MFI 
RELAY

BATTERY

VOLUME AIRFLOW 
SENSOR

POWERTRAIN CONTROL MODULE(PCM)

5 V

37

7

88

63

4

3

2

5

3

1

4

Volume Airflow Sensor Circuit

31

35363738394041 42 43
444546474849

50 51

5253

545556

57 58

32

33 34

D-133

(MU803803)

61
656667686970 717273
74757677787980 8182
8384

858687

8889

62

6364

D-134

(MU803804)

TSB Revision

DIAGNOSTIC TROUBLE CODE PROCEDURES

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.

CIRCUIT OPERATION

• The volume airflow sensor power is supplied from 

the MFI relay (terminal No. 1), and the ground is 
provided on the PCM (terminal No. 88).

• 5-volt power is applied to the volume airflow sen-

sor output terminal (terminal No. 3) from the PCM 
(terminal No. 63). The volume airflow sensor gen-
erates a pulse signal when the output terminal 
and ground are opened/closed (opened/short).

.

TECHNICAL DESCRIPTION

• While the engine is running, the volume airflow 

sensor outputs a pulse signal which corresponds 
to the volume of air flow.

• The PCM checks whether the frequency of this 

signal output by the volume airflow sensor while 
the engine is running is at or above the set value.

• When the throttle position sensor output voltage 

is low, the PCM causes the power transistor to be 
"ON" to send an volume airflow sensor reset sig-
nal to the volume airflow sensor. In response to 
the reset signal, the volume airflow sensor resets 
the filter circuit and improves the ability of the vol-
ume airflow sensor to measure the amount of air 
in a small air intake region.

.

DTC SET CONDITIONS

Check Conditions

• Throttle position sensor output voltage is 1.5 volts 

or higher.

• Engine speed is higher than 2,000 r/min.

Judgement Criteria

• Volume airflow sensor output frequency has con-

tinued to be 60 Hz or lower for 2 seconds.

Check Conditions

• Throttle position sensor output voltage is 2 volts 

or lower.

• Engine speed is lower than 2,000 r/min.

Judgement Criteria

• Volume airflow sensor output frequency has con-

tinued to be 800 Hz or higher for 2 seconds.

.

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

• Volume airflow sensor failed.

• Open or shorted volume airflow sensor circuit, or 

loose connector.

• PCM failed.

• Air leak between volume airflow sensor and throt-

tle body.

AK201039

MFI RELAY

B-22X

AB

CONNECTOR: B-22X

AK201038AH

CONNECTORS: D-133, D-134

PCM

D-134(GR)

D-133(GR)

AK200940AD

B-48(B)

CONNECTOR: B-48

VOLUME AIRFLOW 
SENSOR

TSB Revision

DIAGNOSTIC TROUBLE CODE PROCEDURES

13Ac-4

DIAGNOSIS

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

STEP 1. Using scan tool MB991502, check data list item 12: 
Volume Airflow 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) Start the engine and run at idle.
(3) Set scan tool MB991502 to the data reading mode for item 

12, Volume Airflow Sensor.

(4) Warm up the engine to normal operating temperature: 80

°C 

to 95

°C (176°F to 203°F).

• The standard value during idling should be 10 Hz or 

more.

• When the engine is revved, the frequency should 

increase according to the increase in engine speed.

(5) 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.

STEP 2. Measure the reset signal voltage at volume airflow 
sensor connector B-48 by backprobing.
(1) Do not disconnect the connector B-48.
(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 7 and ground by 

backprobing.

• Voltage should be between 6.0 and 9.0 volts.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 6.0 and 9.0 volts?

YES : Go to Step 5.
NO :  Go to Step 3.

ACX01539

16-PIN

MB991502

AC

AK200937

3

4

5

1

2

6

7

AB

HARNESS 
CONNECTOR: 
COMPONENT SIDE

CONNECTOR: B-48

B-48(B)

AKX01515

6 7

1 2 3 4 5

AKX01515

AJ

B-48 HARNESS 
CONNECTOR: 
HARNESS SIDE