The mass air flow sensor (1) is placed in the stream of intake air. It measures the intake flow rate by measuring a part of the entire intake flow. The mass air flow sensor controls the temperature of the hot wire to a certain amount. The heat generated by the hot wire is reduced as the intake air flows around it. The greater air flow, the greater the heat loss.
Therefore, the electric current supplied to hot wire is changed to maintain the temperature of the hot wire as air flow increases. The
ECM detects the air flow by means of this current change.
DTC Logic
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE 1.PRECONDITIONING
If DTC Confirmation Procedure has been previously conducted, always perform the following before conducting the next test.
Turn ignition switch OFF and wait at least 10 seconds.
Turn ignition switch ON.
Turn ignition switch OFF and wait at least 10 seconds. >> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A
Start engine and warm it up to normal operating temperature.
Run engine for at least 10 seconds at idle speed.
Check 1st trip DTC. Is 1st trip DTC detected?
YES >> Go to Diagnosis Procedure.
NO-1 >> With CONSULT-III: GO TO 3.
NO-2 >> Without CONSULT-III: GO TO 5. 3.CHECK MASS AIR FLOW SENSOR FUNCTION
Turn ignition switch ON.
Start engine and warm it up to normal operating temperature. If engine cannot be started, go to Diagnosis Procedure.
Select "MAS A/F SE-B1" in "DATA MONITOR" mode with CONSULT-III.
Check the voltage of "MAS A/F SE-B1".
Increases engine speed to approximately 4,000 rpm.
Monitor the linear voltage rise in response to engine speed increases. Is the Inspection result normal?
YES >> GO TO 4.
NO >> Go to Diagnosis Procedure.
4.PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B
Maintain the following conditions for at least 10 consecutive seconds.
CAUTION: Always drive vehicle at a safe speed.
Check 1st trip DTC. Is 1st trip DTC detected?
YES >> Go to Diagnosis Procedure.
NO >> Inspection END 5.PERFORM COMPONENT FUNCTION CHECK FOR MALFUNCTION B
Perform component function check. Refer to Component Function Check.
NOTE:
Use component function check to check the overall function of the mass air flow sensor circuit. During this check, a 1st trip DTC might not be confirmed.
Is the Inspection result normal?
YES >> Inspection END
NO >> Go to Diagnosis Procedure.
Component Function Check 1.PERFORM COMPONENT FUNCTION CHECK FOR MALFUNCTION B With GST
Start engine and warm it up to normal operating temperature.
Select Service $01 with GST.
Check the mass air flow sensor signal with Service $01.
Check for linear mass air flow sensor signal value rise in response to increases to approximately 4,000 rpm in engine speed. Is the Inspection result normal?
YES >> Inspection END
NO >> Go to Diagnosis Procedure.
Diagnosis Procedure 1.Inspection START
Confirm the detected malfunction (A or B). Refer to DTC Logic.
Which malfunction is detected?
A >> GO TO 3.
B >> GO TO 2. 2.CHECK INTAKE SYSTEM
Check the following for connection.
Air duct
Vacuum hoses
Intake air passage between air duct and intake manifold Is the Inspection result normal?
YES >> GO TO 3.
NO >> Reconnect the parts. 3.CHECK GROUND CONNECTION
YES >> GO TO 4.
NO >> Repair or replace ground connection. 4.CHECK MAF SENSOR POWER SUPPLY CIRCUIT
Disconnect mass air flow (MAF) sensor harness connector.
Turn ignition switch ON.
Check the voltage between MAF sensor harness connector and ground.
Is the Inspection result normal?
YES >> GO TO 6.
NO >> GO TO 5. 5.DETECT MALFUNCTIONING PART
Check the following.
Harness connectors E11, F2
Harness for open or short between mass air flow sensor and ECM
Harness for open or short between mass air flow sensor and IPDM E/R >> Repair open circuit, short to ground or short to power in harness or connectors.
6.CHECK MAF SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
Turn ignition switch OFF.
Disconnect ECM harness connector.
Check the continuity between MAF sensor harness connector and ECM harness connector.
Also check harness for short to ground and short to power. Is the Inspection result normal?
YES >> GO TO 7.
NO >> Repair open circuit, short to ground or short to power in harness or connectors. 7.CHECK MAF SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
Check the continuity between MAF sensor harness connector and ECM harness connector.
Also check harness for short to ground and short to power. Is the Inspection result normal?
YES >> GO TO 8.
NO >> Repair open circuit, short to ground or short to power in harness or connectors. 8.CHECK INTAKE AIR TEMPERATURE SENSOR
Refer to See: P0112.
Is the Inspection result normal?
YES >> GO TO 9.
NO >> Replace mass air flow sensor (with intake air temperature sensor). 9.CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR
Refer to See: P0451.
Is the Inspection result normal?
YES >> GO TO 10.
NO >> Replace EVAP control system pressure sensor. 10.CHECK MASS AIR FLOW SENSOR
Refer to Component Inspection.
Is the Inspection result normal?
YES >> GO TO 11.
NO >> Replace mass air flow sensor. 11.CHECK INTERMITTENT INCIDENT
Refer to See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Service Information For Electrical Incident\Intermittent Incident.
>> Inspection END
Component Inspection 1.CHECK MASS AIR FLOW SENSOR-I With CONSULT-III
Reconnect all harness connectors disconnected.
Start engine and warm it up to normal operating temperature.
Connect CONSULT-III and select "DATA MONITOR" mode.
Select "MAS A/F SE-B1" and check indication under the following conditions.
Without CONSULT-III
Reconnect all harness connectors disconnected.
Start engine and warm it up to normal operating temperature.
Check the voltage between ECM harness connector terminals under the following conditions.
Is the Inspection result normal?
YES >> Inspection END
NO >> GO TO 2. 2.CHECK FOR THE CAUSE OF UNEVEN AIR FLOW VIA THE MASS AIR FLOW SENSOR
Check for the cause of uneven air flow via the mass air flow sensor. Refer to the following.
Crushed air ducts
Malfunctioning seal of air cleaner element
Uneven dirt of air cleaner element
Improper specification of intake air system parts Is the Inspection result normal?
YES >> GO TO 4.
NO >> GO TO 3. 3.CHECK MASS AIR FLOW SENSOR-II With CONSULT-III
Repair or replace malfunctioning part.
Start engine and warm it up to normal operating temperature.
Connect CONSULT-III and select "DATA MONITOR" mode.
Select "MAS A/F SE-B1" and check indication under the following conditions.
Without CONSULT-III
Repair or replace malfunctioning part.
Start engine and warm it up to normal operating temperature.
Check the voltage between ECM harness connector terminals under the following conditions.
Is the Inspection result normal?
YES >> Inspection END
NO >> GO TO 4. 4.CHECK MASS AIR FLOW SENSOR-III With CONSULT-III
Turn ignition switch OFF.
Disconnect mass air flow sensor harness connector and reconnect it again.
Start engine and warm it up to normal operating temperature.
Connect CONSULT-III and select "DATA MONITOR" mode.
Select "MAS A/F SE-B1" and check indication under the following conditions.
Without CONSULT-III
Turn ignition switch OFF.
Disconnect mass air flow sensor harness connector and reconnect it again.
Start engine and warm it up to normal operating temperature.
Check the voltage between ECM harness connector terminals under the following conditions.
Is the Inspection result normal?
YES >> Inspection END
NO >> Clean or replace mass air flow sensor.
