P0102 Mass or Volume Air Flow Circuit Low Input

COMPONENT LOCATION

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GENERAL DESCRIPTION
The Mass Air Flow Sensor (MAFS) is located between the air cleaner assembly and the throttle body. The MAFS uses a hot film type sensing element to measure the mass of intake air entering the engine. This hot film type air flow sensor consists of a hot film sensor, housing and metering ducts. Mass air flow rate is measured by detection of heat transfer from a hot film probe. The change in air flow rate causes change in the amount of heat being transferred from the hot film probe surface to the air. A large amount of intake air represents acceleration or high load conditions while a small amount of intake air represents deceleration or idle. The mass of intake air should increase at acceleration and be stable during constant engine speed. The ECM uses this information to determine the injection duration and ignition timing for the desired air/fuel ratio.
DTC DESCRIPTION
If ECM detects that frequency signal of MAFS is lower than1000 Hz for more than 75 second during one dignostic test(125 second) while enable condition is me,t ECM determines that a fault exists and a DTC is stored.
MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC DETECTING CONDITION
 
ItemDetecting ConditionPossible cause
DTC Strategy● Compares the airmeter input frequency to a low limit● Poor Connection
● Open or short in harness
● MAFS
● ECM
Enable Conditions● Engine Speed ≥ 500 rpm
● Engine Running Time ≥ 5 second
● Ignition Voltage ≥ 11V
Threshold value● MAF frequency signal < 1000Hz
Diagnosis Time● Continuous (More than 75 second failure for every 125 second tests )
MIL On Condition● 2 Driving Cycles

 

SPECIFICATION
 
Air Flow (kg/h)Frequency (Hz)Air Flow (kg/h)Frequency (Hz)Air Flow (kg/h)Frequency (Hz)
0 kg/h720 ~ 880Hz43.2 kg/h3,975Hz270.0 kg/h7,219Hz
12.6 kg/h2,595Hz57.6 kg/h4,361Hz360.0 kg/h7,945Hz
18.0 kg/h2,930Hz72.0 kg/h4,683Hz486.0 kg/h8,736Hz
23.4 kg/h3,208Hz108.0 kg/h5,362Hz666.0 kg/h9,660Hz
32.4 kg/h3,609Hz198.0 kg/h6,527Hz900.0 kg/h10,613Hz

 

SCHEMATIC DIAGRAM

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TERMINAL AND CONNECTOR INSPECTION
1.
Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3.
Has a problem been found?
YES
▶ Repair as necessary 
NO
▶ Go to ” Power Circuit Inspection ” procedure.
POWER SUPPLY CIRCUIT INSPECTION
1.
IG “OFF” and Disconnect MAFS connector.
2.
IG “ON” & ENG “OFF”
3.
Measure voltage between terminal 2 of MAFS harness connector and chassis ground
Specification : B+

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4.
Is the measured voltage within specification ?
YES
▶ Go to “Signal Circuit Inspection” Procedure.
NO
▶ Check fuse between MAFS and main relay is open or not installed.
▶ Repair open in power harness between MAFS and main relay.
SIGNAL CIRCUIT INSPECTION
1.
Check voltage
(1)
IG “OFF” and disconnect MAFS connector.
(2)
IG “ON’ & ENG “OFF”.
(3)
Measure voltage between terminal 1 of MAFS harness connector and chassis ground.
Specification : Approx. 5V

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(4)
Is the measured voltage within specification ?
YES
▶ Go to “Ground circuit inspection” procedure.
NO
▶ If the measured voltage is “0”, go to “Check open in harness” as follows. If the measured voltage is over “5V”, go to ” Check short to battery in harness” as follows.
2.
Check short to battery in harness
(1)
IG “OFF” and disconnect MAFS and ECM connector.
(2)
Measure resistance between terminal 1 and 2 of MAFS harness connector.
(3)
Measure resistance between terminal 1 and 4 of MAFS harness connector.
Specification : Infinite

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(4)
Is the measured resistance within specification ?
YES
▶ Go to “Check short to ground in harness” as follows.
NO
▶ Repair short to battery in harness.
3.
Check short to ground in harness
(1)
IG “OFF” and disconnect MAFS and ECM connector.
(2)
Measure resistance between terminal 1 of MAFS harness connector and chassis ground.
Specification : Infinite

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(3)
Is the measured resistance within specification ?
YES
▶ Go to “Check open in harness” as follows.
NO
▶ Repair short to ground in harness 
 
4.
Check open in harness
(1)
IG “OFF” and disconnect MAFS and ECM connector.
(2)
Measure resistance between terminal 1 of MAFS harness connector and terminal 47 of ECM harness connector.
Specification : Approx. below 1Ω.

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(3)
Is the measured resistance within specification ?
YES
▶ Go to “Ground circuit Inspection” procedure.
NO
▶ Repair open in harness .
GROUND CIRCUIT INSPECTION
1.
IG “OFF” and disconnect MAFS connector.
2.
Measure voltage between terminal 1 of MAFS harness connector and chassis ground.
3.
Measure voltage between terminal 1 and 3 of MAFS harness connector.
Specification : Voltage difference between Measurement “A” and “B” is below 200mV.

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4.
Is the measured voltage within specification ?
YES
▶ Go to “Component Inspection” procedure.
NO
▶ Repair contact resistance or open in harness.

 

 

 

 

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