P0101
DTC P0101: Mass Airflow Circuit Range/Performance ProblemMass Airflow Sensor Circuit (Part 1):
Mass Airflow Sensor Circuit (Part 2):
CIRCUIT OPERATION
- The mass airflow sensor power is supplied from the MFI relay (terminal No. 2), and the ground is provided on the ECM (terminal No. 88).
- A voltage that is according to the mass airflow rate is sent to the ECM (terminal No. 87) from the mass airflow sensor output terminal (terminal No. 3).
TECHNICAL DESCRIPTION
- While the engine is running, the mass airflow sensor outputs voltage which corresponds to the mass airflow rate.
- The ECM checks whether the voltage output by the mass airflow sensor while the engine is running is within a specified range.
DESCRIPTIONS OF MONITOR METHODS
Compare load value with mass airflow sensor output voltage.
MONITOR EXECUTION
Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Not applicable
Sensor (The sensor below is determined to be normal)
- Throttle position sensor
DTC SET CONDITIONS [ Range/Performance problem - low input]
Logic Flow Chart:
Check Conditions
- Throttle position sensor output voltage is 1.5 volt or higher.
- Mass airflow sensor output voltage is 0.2 volt or higher.
Judgement Criterion
- Mass airflow sensor output voltage has continued to be 1.8 volts or lower for 2 seconds.
DTC SET CONDITIONS [ Range/Performance problem - high input]
Logic Flow Chart:
Check Conditions
- Throttle position sensor output voltage is 1.0 volt or lower.
- Mass airflow sensor output voltage is 4.9 volts or lower.
Judgement Criterion
- Mass airflow sensor output voltage has continued to be 3.5 volts or higher for 2 seconds.
OBD-II DRIVE CYCLE PATTERN
Refer to MFI Diagnostic Function-OBD-II Drive Cycle-Pattern 7. OBD-II Drive Cycle
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Mass airflow sensor failed.
- Connector damage
- Harness damage
- ECM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness
STEP 1. Using scan tool MB991958, check data list item 10: Mass Airflow Sensor.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991958 to the data reading mode for item 10, Mass Airflow Sensor.
4. Warm up the engine to normal operating temperature: 80 °C to 95 °C (176 °F to 203 °F).
- The standard value during idling should be between 1,350 and 1,670 millivolts.
- When the engine is revved, the mass airflow rate should increase according to the increase in engine speed.
5. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES : It can be assumed that this malfunction is intermittent. Refer to General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points-How to Cope with Intermittent Malfunctions.
NO : Go to Step 2.
STEP 2. Check harness connector A-07 at the mass airflow sensor and harness connector B-11 at the ECM for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 3.
NO : Repair it. Refer to General (Electrical), Harness Connector Inspection. Then go to Step 6.
STEP 3. Check for harness damage between the mass airflow sensor connector A-07 and the ECM connector B-11.
1. Disconnect the mass airflow sensor connector A-07 and the ECM connector B-11.
2. Measure the resistance between the mass airflow sensor connector A-07 and the ECM connector B-11.
a. Connector A-07 (terminal No. 3) and Connector B-11 (terminal No. 87).
b. Connector A-07 (terminal No. 4) and Connector B-11 (terminal No. 88).
- Should be less than 2 ohms.
Q: Is the measured resistance less than 2 ohms?
YES : Go to Step 4.
NO : Repair it. Then go to Step 6.
STEP 4. Check for harness the MFI relay connector A-33X (terminal No. 2) and the mass airflow sensor connector A-07 (terminal No. 2).
1. Disconnect the MFI relay connector A-33X and the mass airflow sensor connector A-07.
2. Measure the resistance between the MFI relay connector A-33X (terminal No. 2) and the mass airflow sensor A-07 (terminal No. 2).
- Should be less than 2 ohms.
Q: Is the measured resistance less than 2 ohms?
YES : Go to Step 5.
NO : Repair it. Then go to Step 6.
STEP 5. Replace the mass airflow sensor.
1. Replace the mass airflow sensor.
2. Carry out a test drive with the drive cycle pattern. Refer to MFI Diagnostic Function-OBD-II Drive Cycle-Pattern 7. OBD-II Drive Cycle
3. Check the diagnostic trouble code (DTC).
Q: Is DTC P0101 set?
YES : Replace the ECM. When the ECM is replaced,register the ID code. Refer to Diagnosis -ID Codes Registration Judgment Table [Vehicles with KOS] or Diagnosis-ID Codes Registration Judgment Table [Vehicles with WCM]. Then go to Step 6.
NO : The inspection is complete.
STEP 6. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to MFI Diagnostic Function-OBD-II Drive Cycle-Pattern 7. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0101 set?
YES : Retry the troubleshooting.
NO : The inspection is complete.