P0100
Component Description
The mass air flow sensor is placed in the stream of intake air. It measures the intake flow rate by measuring a part of the entire intake flow. It consists of a hot wire that is supplied with electric current from the ECM. The temperature of the hot wire is controlled by the ECM a certain amount. The heat generated by the hot wire is reduced as the intake air flows around it. The more air, the greater the heat loss.
Therefore, the ECM must supply more electric current to maintain the temperature of the hot wire as air flow increases. The ECM detects the air flow by means of this current change.
CONSULT-II Reference Value in Data Monitor Mode
Specification data are reference values.
On Board Diagnosis Logic
Malfunction is detected when (Malfunction A) an excessively high voltage from the sensor is sent to ECM when engine is not running, (Malfunction B) an excessively low voltage from the sensor is sent to ECM when engine is running, (Malfunction C) a high voltage from the sensor is sent to ECM under light load driving condition, (Malfunction D) a low voltage from the sensor is sent to ECM under heavy load driving condition, (Malfunction E) a voltage from the sensor is constantly approx. 1.0 V when engine is running.
FAIL-SAFE MODE
When the malfunction B is detected, the ECM enters fail-safe mode and the MIL lights up.
Detected items Engine operating condition in fail-safe mode
Mass air flow sensor circuit Engine speed will not rise more than 2,400 rpm due to the fuel cut.
Possible Cause
MALFUNCTION A OR C
- Harness or connectors
(The sensor circuit is open or shorted. )
- Mass air flow sensor
MALFUNCTION B, D OR E
- Harness or connectors
(The sensor circuit is open or shorted. )
- Intake air leaks
- Mass air flow sensor
DTC Confirmation Procedure
Perform "PROCEDURE FOR MALFUNCTION A" first. If the 1st trip DTC cannot be confirmed, perform "PROCEDURE FOR MALFUNCTION B AND E".
If there is no problem on "PROCEDURE FOR MALFUNCTION B AND E", perform "PROCEDURE FOR MALFUNCTION C". If there is no problem on "PROCEDURE FOR MALFUNCTION C", perform "PROCEDURE FOR MALFUNCTION D".
NOTE: If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch "OFF" and wait at least 10 seconds before conducting the next test.
PROCEDURE FOR MALFUNCTION A
With CONSULT-II
1. Turn ignition switch "ON".
2. Select "DATA MONITOR" mode with CONSULT-II.
3. Wait at least 6 seconds.
4. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
With GST
Follow the procedure "With CONSULT-II" above.
PROCEDURE FOR MALFUNCTION B AND E
With CONSULT-II
1. Turn ignition switch "ON".
2. Select "DATA MONITOR" mode with CONSULT-II.
3. Start engine and wait 5 seconds at most.
4. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
With GST
Follow the procedure "With CONSULT-II" above.
NOTE: If 1st trip DTC is confirmed after more than 5 seconds, there may be malfunction C.
PROCEDURE FOR MALFUNCTION C
NOTE: If engine will not start or stops soon, wait at least 10 seconds with engine stopped (Ignition switch "ON") instead of running engine at idle speed.
With CONSULT-II
1. Turn ignition switch "ON".
2. Select "DATA MONITOR" mode with CONSULT-II.
3. Start engine and warm it up to normal operating temperature.
4. Run engine for at least 10 seconds at idle speed.
5. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
With GST
Follow the procedure "With CONSULT-II" above.
PROCEDURE FOR MALFUNCTION D
CAUTION: Always drive vehicle at a safe speed.
With CONSULT-II
1. Turn ignition switch "ON".
2. Start engine and warm it up to normal operating temperature.
If engine cannot be started, go to "Diagnostic Procedure" below.
3. Select "DATA MONITOR" mode with CONSULT-II.
4. Check the voltage of MAS AIR/FL SE with "DATA MONITOR".
5. Increases engine speed to about 4,000 rpm.
6. Monitor the linear voltage rise in response to engine speed increases.
If NG, go to "Diagnostic Procedure" below.
If OK, go to following step.
7. Maintain the following conditions for at least 10 consecutive seconds.
CKPS.RPM (POS) More than 2,000 rpm
THRTL POS SEN More than 3 V
Selector lever Suitable position
Driving location Driving vehicle uphill (Increased engine load) will help maintain the driving conditions required for this test.
8. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
Overall Function Check
PROCEDURE FOR MALFUNCTION D
Use this procedure to check the overall function of the mass air flow sensor circuit. During this check, a 1st trip DTC might not be confirmed.
With GST
1. Start engine and warm it up to normal operating temperature.
2. Select "MODE 1" with GST.
3. Check the mass air flow sensor signal with "MODE 1".
4. Check for linear mass air flow sensor signal value rise in response to increases to about 4,000 rpm in engine speed.
5. If NG, go to "Diagnostic Procedure" below.
EC-MAFS-01:
EC-MAFS-01 - Connector View:
Wiring Diagram
ECM TERMINALS AND REFERENCE VALUE MEASURED BETWEEN EACH TERMINAL AND 48.:
Diagnostic Procedure
Diagnostic Procedure Step 1:
Diagnostic Procedure Step 2:
Diagnostic Procedure Step 3:
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Diagnostic Procedure Step 6:
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Diagnostic Procedure Step 9:
