3.
Has a problem been found?
Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Go to "Component Inspection " procedure.
MAFS (Mass Air Flow Sensor) has abuilt-in intake air temperature sensor and is located between the air cleaner assembly and the throttle device. The MAFS uses a hot film type sensing-element to measure the mass of intake air entering the engine. And send the signal to ECM.
A large amount of intake air represents acceleration or high load conditions while a small amount of intake air represents deceleration or idle.
The ECM uses this information to control the EGR solenoid valve and correct the fuel amount.
If the signal exceeds threshold value, the ECM judged this as a fault and DTC is set.
Item | Detecting Condition | Cause |
DTC Strategy | ● Rationality check | ● Air Leakage ● Short to battery in signal circuit ● Faulty MAFS ● Faulty EGR ● Faulty ECM |
Enable Conditions | ● 2050 ＜ Engine speed ＜ 2600 rpm and injection quantity ＜ 0 mg/st, barometric pressure ＞ 750 hpa and -50°C ＜ WTS ＜ 120°C only | |
Threshold Value | ● Mass air flow ＞ 950 mg/st | |
Diagnostic Time | ● 5 sec. | |
MIL Fuel Limit Fuel Cut EGR Off | ● Yes ● Yes ● No ● Yes | |
Fail safe | ● EGR valve deactivited ● Fuel quantity limitation |
MAFS | Idle Position (without EGR) | Idle Position (with EGR) |
Mass air flow | 450~550 mg/stroke | 280~360 mg/stroke |
Ignition "OFF" & Engine "OFF".
Install Scantool and Engine "ON ".
Monitor that Current data is changing without EGR actuator operation or with EGR actuator operation while idling engine speed.
Fig 1) Normal value without EGR actuator : Approx. 450 ~ 550 mg/stroke
Fig 2) Normal value with EGR actuator : Approx. 280 ~ 360 mg/stroke
Is Current data displayed correctly ?
▶ Fault is intermittent caused by poor contact in the sensor’s and/or ECM’s connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification vehicle Repair" procedure.
▶ Go to "System Inspection" procedure.
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.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Go to "Component Inspection " procedure.
Check Air Leakage.
Check intake and MAFS for source of any air leaks.
Check any cracks or deformation on MAFS and check that MAFS is installed in correct position.
Verify oil cap and dipstick are properly installed and oil cap screwed on completely.
Has a problem been found?
▶ Repair or Replace as necessary and go to "Verification of Vehicle Repair" procedure .
▶ Go to "APS Inspection" procedure.
Check APS
Ignition OFF.
Connect Scantool and monitor Accel Position Sensor parameters on Current Data.
Specification : Approx. 0.4 ~ 0.7V(at Idle), 4.4 ~ 4.8V(Wide Open Throttle)
Is parameter displayed within specifications ?
▶ Go to "Check EGR solenoid valve operation" as below
▶ Go to "APS Inspection" procedure. For more detail inspection, refer to DTC P0120,P0123, 0220,P0223 and P2123 for APS troubleshooting guide.
Check EGR solenoid valve operation
Ignition "ON" & Engine "ON".
Confirm that EGR solenoid valve Duty is 5% after warming-up Engine.
Be sure that vacuum is felt after disconnecting vaccum hose from EGR solenoid valve.
Check that vacuum is felt in idle after sudden accelleration(EGR solenoid valve Duty : 95%)
EGR DUTY : 5% | EGR DUTY : 95% |
No Vaccum | Vacuum |
Is the vaccum felt from vaccum hose according to EGR DUTY ?
▶ Go to "W/Harness Inspection" procedure.
▶ Check EGR solenoid for contamination, deterioration, or damage. Substitute with a known-good GR and check for proper operation. If the problem is corrected, replace EGR and then go to "Verification of Vehicle Repair" procedure.
Visual Inspection
Ignition "OFF" & Engine "OFF".
Check that arrow mark on the MAFS is indicating correct direction.
Check any contamination, corriosion or damage on connector.
Check that air cleaner is clogged or wet.
Check that MAFS cylinder is deformed, blocked by any foreign material or contaminated.
Hot film can be seriously damaged by foreign material or moisture.
Is the MAFS visually O.K ?
▶ Go to "Check MAFS" as below.
▶ Substitute with a known-good MAFS and check for proper operation.
If the problem is corrected, replace MAFS and then go to "Verification of Vehicle Repair" procedure.
Check MAF.
Engine "ON".
Warm up the engine to normal operating temperature.
Check any leakage on intake system(Leakage or damage on intercooler hose).
Check that EGR operates after sudden accelleration elasped around 90sec.
If necessary, disconnect EGR vaccum hose.
Monitor "MASS AIR FLOW" parameter on the CURRENT DATA.
Specification : 500mg/st ± 50mg/st
Is the current data displayed correctly ?
▶ Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification vehicle Repair" procedure.
▶ Substitute with a known-good MAFS and check for proper operation.
If the problem is corrected, replace MAFS and then go to "Verification of Vehicle Repair" procedure.
After a repair, it is essential to verify that the fault has been corrected.
Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode and then clear DTC.
Operate the vehicle within DTC Enable conditions in General information.
Are any DTCs present ?
Go to the applicable troubleshooting procedure.
System is performing to specification at this time.
