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Component Location

General Description

Air Flow Sensor(MAFS) is digital sensor. Measuring mass of air flow, signal is outputted as frequency(Hz).

ECM performs EGR system feed back control with the information of measured mass air flow. (The role of MAFS in diesel engine is different from gasoline engine. Fuel injection quantity is decided by MAFS signal in gasoline engine.)

When EGR gas(contains no oxygen) flowing into combustion chamber increases, the air passing through MAFS(contains oxygen) decreases. Thus, with the output signal change of MAFS accompanied by EGR actuator actuation, ECM determines the amount of recirculated EGR gas quantity.

note

NOx is produced from the reaction of nitrogen and oxygen. If least intake air required for complete combustion flows into combustion chamber by controlling EGR gas(contains no oxygen) which is recirculated to combustion chamber, NOx decreases because there is no supplementary oxygen to react with nitrogen.

DTC Description

P0103 is set when MAFS output voltage above 1200Hz is detected for more than 0.58 sec. This code is due to excessive output voltage from sensor component or poor connection in sensor circuit.

DTC Detecting Condition

Item	Detecting Condition		Possible Cause
DTC Strategy	● Voltage monitoring		● MAFS circuit ● MAFS component
Enable Conditions	● Engine running
Threshold Value	● Abnormal maximum output signal(Output signal below below 1200Hz )
Diagnostic Time	● 0.6 sec.
Fail Safe	Fuel cut	NO
	EGR Off	YES
	Fuel Limit	YES
	Check Lamp	YES

Specification

Intake air quantity (Kg/h)	Output frequency ( KHz )		Deviation [ % ]
Intake air quantity (Kg/h)	20℃	80℃	Deviation [ % ]
8	1.97		± 3
10	2.01	2.01	± 2
40	2.50	2.50	± 2
105	3.20	3.20	± 2
220	4.30		± 2
480	7.80	7.80	± 2
560	9.50		± 3

Diagnostic Circuit Diagram

Monitor GDS Data

Connect GDS to Data Link Connector (DLC).

Warm engine up to normal operating temperature.

Turn "OFF" electrical devices and A/C.

Monitor "AIR MASS PERCYLINDER" parameter on the GDS.

Specification : When Electric EGR control valve does not operate 5% duty) at idle : 340mg/st ± 50 mg/st

When Electric EGR control valve operates(Approx. 45% duty) at idle : 200ms/st ± 50 mg/st

Fig.1) Check if "AIR MASS PERCYLINDER"l is 340mg/st ± 50mg/st without EEGR operation at warm idle (Electric EGR control valve 5% duty)

Fig.2) Check if "AIR MASS PERCYLINDER"l is 200mg/st ± 50mg/st with EEGR operation at warm idle (Electric EGR control valve approx. 45% duty)

※ Electric EGR control valve operates as decelerating after rapid acceleration when idle EEGR does not operate, Electric EGR control valve operating duty decreases as time goes by. This controlling process lasts for about 1 min. and EElectric EGR control valve turns "OFF" (duty 5% ) after 1 min.

Terminal and Connector Inspection

Electrical systems consist of a lot of harness and connectors, poor connection of terminals can cause various problems and damge of component.

Perform checking procedure as follows.

(1)

Check damage of harness and terminals : Check terminals for contact resistance, corrosion and deformation.

(2)

Check connecting condition of ECM and component connector : Check terminal seperation, damage of locking device and connecting condition between terminal and wiring.

note

Disconnect the pin which requires checking at male connector and insert it to the terminal at female connector for checking connecting condition. ( after checking, reconnect the pin at correct position. )

Is the problem found?

	▶ Repair the trouble causing part and go to "Verification of Vehicle Repair".
	▶ Go to "Power Circuit Inspection".

Power Circuit Inspection

Check power circuit voltage

(1)

IG KEY "OFF", ENGINE "OFF".

(2)

Disconnect MAFS connector.

(3)

IG KEY "ON".

(4)

Measure the voltage between IG power terminal of MAFS harness connector and chassis ground.

(5)

Measure the voltage between power terminal of MAFS harness connector and chassis ground.

Specification : 4.8V~5.1V ( Sensor power )

11.5V~13.0V ( IG Power )

(6)

Is the measured voltage within the specification?

▶ Go to "Signal Circuit Inspection".

▶ When output voltage is not detected at IG power terminal :

☞ Repair open in 'SNSR.2 FUSE (10A)' in E/R junction box and related circuit and go to "Verification of Vehicle Repair".

▶ When output voltage is not detected at power terminal :

☞ Repair open between power terminal of MAFS connector and sensor power terminal of ECM connector (CUD-A), and go to "Verification of Vehicle Repair".

Signal Circuit Inspection

Check signal circuit voltage

(1)

IG KEY "OFF", ENGINE "OFF".

(2)

Disconnect MAFS connector.

(3)

IG KEY "ON".

(4)

Measure the voltage between signal terminal of MAFS connector and chassis ground.

Specification : 4.8V~5.1V

(5)

Is the measured resistance within the specification?

	▶ Go to "Ground Circuit Inspection".
	▶ Go to "2. Check open in signal circuit" as follows.

Check open in signal circuit

(1)

IG KEY "OFF", ENGINE "OFF".

(2)

Disconnect MAFS sensor connector and ECM connector.

(3)

Check continuity between siganl terminal of MAFS harness connector and signal terminal of ECM harness connector.

Specification : Continuity ( below 1.0Ω )

(4)

Is the measured resistance within the specification?

	▶ Go to "3. Check short to ground in signal circuit" as follows.
	▶ Repair open in signal circuit and go to "Verification of Vehicle Repair".

Check short to ground in signal circuit

(1)

IG KEY "OFF", ENGINE "OFF".

(2)

Disconnect MAFS sensor connector and ECM connector.

(3)

Check continuity between siganl terminal of MAFS harness connector and chassis ground.

Specification : Discontinuity(Infinite Ω )

(4)

Is the measured resistance within the specification?

	▶ Go to "Ground Circuit Inspection".
	▶ Repair short to ground in signal circuit and go to "Verification of Vehicle Repair".

Ground Circuit Inspection

IG KEY "OFF", ENGINE "OFF".

Disconnect MAFS connector.

IG KEY "ON".

Measure the voltage between power terminal of MAFS harness connector. [ TEST "A" ]

Measure the voltage between power terminal of MAFS harness connector and ground terminal of MAFS harness connector. [ TEST "B" ]

( MAFS power terminal : Check + prove , MAFS ground terminal : Check - prove )

Specification : [TEST "A"] Voltage - [TEST "B"] Voltage = below 200mV

Is the measured voltage within the specification?

▶ Go to "Component Inspection".

▶ When "B" voltage is not detected : Repair open in ground circuit and go to "Verification of Vehicle Repair".

▶ When the voltage difference between "A" and "B" is above 200mV : Eliminate the causes of excessive resistance and go to "Verification of Vehicle Repair".

Component Inspection

IG KEY "OFF", ENGINE "OFF".

Check that MAFS is installed in correctly according to the direction of arrow on MAFS assy’.

Check contamination of air cleaner filter.

IG KEY "ON", ENGINE "ON".

Let IDLE RPM last after warming engine up.

Check the leakage of intake system(the leakage or damage of intercooler).

Check that VGT operates correctly.(Check if vacuum operating state of VGT Control solenoid valve is appropriate, if VGT diaphragm and unison ring are stuck.)

Check that Electric EGR control valve does not operate.

( Electric EGR control valve turns "OFF" and 6% duty is outputted 1 min after rapid acceleration. Disconnect EElectric EGR control valve connector if needed. )

Monitor signal voltage of MAFS when engine speed lasts at approx. 800RPM using GDS.

10.

Check MAFS output signal at idle after rapid acceleration.(Electric EGR control valve duty 50%)

Specification : When Electric EGR control valve does not operate (6%) at idle : 340mg/st ± 50 mg/st

EEGR When EElectric EGR control valve operates(50%) at idle : 200ms/st ± 50 mg/st

11.

Is output signal within the specification?

	▶ Go to "Verification of Vehicle Repair".
	▶ Replace MAFS assy' and go to "Verification of Vehicle Repair".

Verification of Vehicle Repair

After a repair, it is essential to verify that the fault is corrected.

After connecting GDS select "Diagnostic Trouble Codes(DTCs)" mode to and then clear DTC.

Drive the vehicle within DTC Enable conditions in General information.

After selecting "Diagnostic Trouble Codes(DTCs)" mode and check DTC is recorded again.

Are any DTCs recorded ?

	▶ Go to the DTC guide of recorded NO. in GDS.
	▶ System operates within specification.