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 electric current which corresponds to the mass airflow rate.
- The ECM converts the electric current into the voltage and checks whether the voltage is within a specified range while the engine is running.
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 - high]
Logic Flow Chart
Logic Flow Chart:
Check Conditions
- Throttle position sensor output voltage is 0.8 volt or lower.
- Mass airflow sensor output voltage is 4.9 volts (corresponding to an air flow rate of 387 g/sec) or lower.
Judgement Criterion
- Mass airflow sensor output voltage has continued to be 2.5 volts (corresponding to an air flow rate of 37 g/sec) or higher for 2 seconds.
DTC SET CONDITIONS [Range/Performance problem - low ]
Logic Flow Chart
Logic Flow Chart:
Check Conditions
- Engine speed is 1,500 r/min or higher.
- Throttle position sensor output voltage is 1.5 volts or higher.
- Mass airflow sensor output voltage is 0.2 volt (corresponding to an air flow rate of 0 g/sec) or higher.
Judgement Criterion
- Mass airflow sensor output voltage has continued to be 1.8 volts (corresponding to an air flow rate of 10 g/sec) or lower for 2 seconds.
FAIL-SAFE AND BACKUP FUNCTION
- None
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 6. OBD- II Drive Cycle
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Mass airflow sensor failed.
- Mass airflow sensor circuit harness damage, or connector 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 A
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 1,300 and 1,650 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.
NO : Go to Step 2.
STEP 2. Check harness connector A-07 at mass airflow sensor and harness connector A-34X at MFI relay for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 3.
NO : Repair or replace it. Then go to Step 8.
STEP 3. Check for harness damage between MFI relay connector A-34X (terminal No. 2) and mass airflow sensor connector A-07 (terminal No. 2).
Q: Is the harness wire in good condition?
YES : Go to Step 4.
NO : Repair it. Then go to Step 8.
STEP 4. Check harness connector B-10 at ECM for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 5.
NO : Repair or replace it. Then go to Step 8.
STEP 5. Check the continuity at mass airflow sensor harness side connector A-07.
1. Disconnect the connector A-07 and measure at the harness side.
2. Check for the continuity between terminal No. 4 and ground.
- Continuity (2 ohms or less)
Q: Does continuity exist?
YES : Go to Step 6.
NO : Repair harness wire between mass airflow sensor connector A-07 (terminal No. 4) and ECM connector B-10 (terminal No. 88) because of harness damage. Then go to Step 8.
STEP 6. Check for harness damage between mass airflow sensor connector A-07 (terminal No. 3) and ECM connector B-10 (terminal No. 87).
Q: Is the harness wire in good condition?
YES : Go to Step 7.
NO : Repair it. Then go to Step 8.
STEP 7. Replace the mass airflow sensor.
1. Replace the mass airflow sensor.
2. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 6. 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. Then go to Step 8.
NO : The inspection is complete.
STEP 8. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 6. 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.