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. 4), and the ground is provided on the PCM (terminal No. 96).
- A voltage related to the mass airflow rate is sent to the PCM (terminal No. 63) 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 PCM 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)
- Not applicable
Sensor (The sensor below is determined to be normal)
- Throttle position sensor
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow Chart
Check Conditions
- Throttle position sensor output voltage is 1.0 volt or lower.
Judgement Criteria
- Mass airflow sensor output voltage has continued to be 3.5 volts or higher for 2 seconds.
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow Chart
Check Conditions
- Throttle position sensor output voltage is 1.5 volts or higher.
Judgement Criteria
- Mass airflow sensor output voltage has continued to be 1.82 volts or lower for 2 seconds.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
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.
- PCM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
STEP 1. Using scan tool MB991958, check data list item 12: 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 12, Mass Airflow Sensor.
4. Warm up the engine to normal operating temperature: 85 °C to 95 °C (185 °F to 203 °F).
- The standard value during idling should be between 2.0 and 6.0 g/sec.
- 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 How to Use Troubleshooting/Inspection Service Points.
NO: Go to Step 2.
STEP 2. Check harness connector B-04 at mass airflow sensor and harness connector B-12X at MFI relay for damage.
Q: Is the connector in good condition?
YES: Go to Step 3.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 9.
STEP 3. Check for harness damage between MFI relay connector B-12X (terminal No. 4) and mass airflow sensor connector B-04 (terminal No. 2).
Q: Is the harness wire in good condition?
YES: Go to Step 4.
NO: Repair it. Then go to Step 9.
STEP 4. Check harness connector C-111 at PCM for damage.
Q: Is the connector in good condition?
YES: Go to Step 5.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 9.
STEP 5. Check the continuity at mass airflow sensor harness side connector B-04.
1. Disconnect the connector B-04 and measure at the harness side.
2. Check for the continuity between terminal No. 4 and ground.
- Should be less than 2 Ohms.
Q: Does continuity exist?
YES: Go to Step 6.
NO: Check harness wire between mass airflow sensor connector B-04 (terminal No. 4) and PCM connector C-111 (terminal No. 96) because of harness damage. Then go to Step 9.
STEP 6. Check harness connector C-112 at PCM for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 7.
NO: Repair it. Then go to Step 9.
STEP 7. Check for harness damage between mass airflow sensor connector B-04 (terminal No. 3) and PCM connector C-112 (terminal No. 63).
Q: Is the harness wire in good condition?
YES: Go to Step 8.
NO: Repair it. Then go to Step 9.
STEP 8. 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 - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
3. Check the diagnostic trouble code (DTC).
Q: Is DTC P0101 set?
YES: Replace the PCM. Then go to Step 9.
NO: The inspection is complete.
STEP 9. 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 - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0101 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.