P0101
1UR-FE ENGINE CONTROL: SFI SYSTEM: P0101: Mass Air Flow Circuit Range / Performance Problem
P0101 - Mass Air Flow Circuit Range / Performance Problem
DESCRIPTION
The mass air flow meter is a sensor that measures the amount of air flowing through the throttle valve.
The ECM uses this information to determine the fuel injection time and to provide the appropriate air-fuel ratio.
Inside the mass air flow meter, there is a heated platinum wire which is exposed to the flow of intake air.
By applying a specific electrical current to the wire, the ECM heats it to a given temperature. The flow of incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to the wire and internal thermistor. The voltage level is proportional to the airflow through the sensor, and the ECM uses it to calculate the intake air volume.
The circuit is constructed so that the platinum hot wire and temperature sensor create a bridge circuit, and the power transistor is controlled so that the potentials of A and B remain equal to maintain the predetermined temperature.
HINT
When either of these DTCs is stored, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is calculated by the ECM according to the engine speed and throttle valve position. The ECM continues operating in fail-safe mode until a pass condition is detected.
MONITOR DESCRIPTION
The mass air flow meter is a sensor that measures the amount of air flowing through the throttle valve. The ECM uses this information to determine the fuel injection time and to provide an appropriate air-fuel ratio. Inside the mass air flow meter, there is a heated platinum wire which is exposed to the flow of intake air. By applying a specific electrical current to the wire, the ECM heats it to a specific temperature. The flow of incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to the wire and internal thermistor. The voltage level is proportional to the airflow through the sensor and the ECM uses it to calculate the intake air volume.
The ECM monitors the average engine load value ratio to check the mass air flow meter for malfunctions. The average engine load value ratio is obtained by comparing the average engine load calculated from the mass air flow meter output to the average engine load estimated from the driving conditions, such as the engine speed and throttle valve opening angle. If the average engine load value ratio is below the threshold value, the ECM determines that the intake air volume is low, and if the average engine load value ratio is above the threshold value, the ECM determines that the intake air volume is high.
If this is detected in 2 consecutive driving cycles, the MIL is illuminated and a DTC is stored.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
WIRING DIAGRAM
CONFIRMATION DRIVING PATTERN
- Connect the Techstream to the DLC3.
- Turn the engine switch on (IG).
- Turn the Techstream on.
- Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).
- Turn the engine switch off and wait for at least 30 seconds.
- Turn the engine switch on (IG) and turn the Techstream on.
- Start the engine and warm it up until the engine coolant temperature reaches 70°C (158°F) or higher [A].
- Drive the vehicle at approximately 80 km/h (50 mph) to 112 km/h (70 mph) for 5 minutes or more [B].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
HINT
Drive while keeping the engine load as stable as possible.
- Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [C].
- Read the pending DTCs.
HINT
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
- Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
- Input the DTC: P0101.
- Check the DTC judgment result.
HINT
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [B] through [C] again.
- If no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.
HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
INSPECTION PROCEDURE
HINT
Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
1. CHECK FOR ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0101)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(e) Read DTCs.
Result
HINT
If any DTCs other than P0101 are output, troubleshoot those DTCs first.
B -- GO TO DTC CHART SFI System
A -- Continue to next step.
2. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leaks Testing and Inspection.
OK:
No leaks in air induction system.
NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK -- Continue to next step.
3. CHECK PCV HOSE CONNECTIONS
(a) Check the PCV hose connections.
OK:
PCV hose is connected correctly and is not damaged.
NG -- REPAIR OR REPLACE PCV HOSE Removal
OK -- Continue to next step.
4. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION)
(a) Connect the Techstream to the DLC3.
(b) Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.
HINT
- When performing the Active Test, make sure the shift lever is in P or N.
- The A/C switch and all accessory switches should be off.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position.
(e) Confirm that Throttle Idle Position is ON and check the engine idling condition and the value of MAP in the Data List while performing the Active Test.
HINT
- Do not leave the EGR valve open for 10 seconds or more during the Active Test.
- Be sure to return the EGR valve to step 0 when the Active Test is completed.
OK:
MAP and idling condition change in response to EGR step position as follows.
Standard:
NG -- INSPECT EGR VALVE ASSEMBLY
OK -- REPLACE MASS AIR FLOW METER ASSEMBLY
5. INSPECT EGR VALVE ASSEMBLY
(a) Remove the EGR valve assembly Removal.
(b) Check if the EGR valve is stuck open.
OK:
EGR valve is tightly closed.
NG -- REPLACE EGR VALVE ASSEMBLY Removal
OK -- Continue to next step.
6. REPLACE MASS AIR FLOW METER ASSEMBLY
(a) Replace the mass air flow meter assembly Removal.
NEXT -- Continue to next step.
7. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Clear the DTCs DTC Check / Clear.
(e) Turn the engine switch off and wait for 30 seconds.
(f) Turn the engine switch on (IG) and turn the Techstream on.
(g) Start the engine and warm it up.
(h) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
(i) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
(j) Input the DTC: P0101.
(k) Check the DTC judgment result.
Result
NEXT -- END