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 ECM
- A voltage that is according to the mass airflow rate is sent to the ECM
TECHNICAL DESCRIPTION
- While the engine is running, the mass airflow sensor outputs voltage which corresponds to the mass airflow rate.
- The ECM
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
Logic Flow Chart:
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.
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow Chart
Check Conditions
- Throttle position sensor output voltage is 1.5 volts 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.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function OBD-II Drive Cycle Pattern 7 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.
- ECM failed.
- 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 degrees to 95 degrees C (185 degrees F to 203 degrees 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.
NO: Go to Step 2.
STEP 2. Check harness connector B-125 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. 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-125 (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-139 at ECM
Q: Is the connector in good condition?
YES: Go to Step 5.
NO: Repair or replace it. Then go to Step 9.
STEP 5. Check the continuity at mass airflow sensor harness side connector B-125.
1. Disconnect the connector B-125 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-125 (terminal No. 4) and ECM connector C-139
STEP 6. Check harness connector C-137 at ECM
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-125 (terminal No. 3) and ECM
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 - Pattern 7 OBD-II Drive Cycle Pattern Lists.
3. Check the diagnostic trouble code (DTC).
Q: Is DTC P0101 set?
YES: Replace the ECM or 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 - Pattern 7 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.