P0102

DTC P0102: Mass Airflow Circuit Low Input

CAUTION:
If DTC P0102 has been set, TCL related DTC U1120 is also set. After P0102 has been diagnosed, don't forget to erase DTC U1120.


















CIRCUIT OPERATION

- The mass airflow sensor power is supplied from the MFI relay (terminal No. 4), and the ground is provided on the ECM [M/T] or the PCM [A/T] (terminal No. 69).
- A voltage that is according to the mass airflow rate is sent to the ECM [M/T] or the PCM [A/T] (terminal No. 108) 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 [M/T] or the PCM [A/T] checks whether the voltage output by the mass airflow sensor while the engine is running is within a specified range.

DESCRIPTIONS OF MONITOR METHODS

Mass airflow sensor output voltage is out of specified range.

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)

- Not applicable

DTC SET CONDITIONS

Logic Flow Chart





Check Condition

- 3 seconds or more have passed since the ignition switch was turned to "ON" position.
Judgement Criterion

- Mass airflow sensor output voltage has continued to be lower than 0.2 volt for 2 seconds.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 23 Monitors, Trips, Drive Cycles and Readiness Codes .

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)

- Mass airflow sensor failed.
- Open or shorted mass airflow sensor circuit, or connector damage.
- ECM failed. [M/T]
- PCM failed. [A/T]

DIAGNOSIS

Required Special Tools:

- MB991958: Scan tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
- MB991923: Power Plant ECU Check 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 1,300 and 1,620 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. How to Cope With Intermittent Malfunctions.

NO Go to Step 2.

STEP 2. Check harness connector B-09 at mass airflow sensor for damage.





Q. Is the harness connector in good condition?

YES Go to Step 3.

NO Repair or replace it. Harness Connector Inspection.
Then go to Step 11.

STEP 3. Measure the power supply voltage at mass airflow sensor harness side connector B-09.









(1)Disconnect the connector B-09 and measure at the harness side.
(2)Turn the ignition switch to the "ON" position.
(3)Measure the voltage between terminal No. 2 and ground.

- Voltage should be battery positive voltage.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is battery positive voltage (approximately 12 volts) present?

YES Go to Step 5.

NO Go to Step 4.

STEP 4. Check harness connector B-16X at MFI relay for damage.





Q. Is the harness connector in good condition?

YES Repair harness wire between MFI relay connector B-16X (terminal No. 4) and mass airflow sensor connector B-09 (terminal No. 2) because of open circuit or short circuit to ground.
Then go to Step 11.

NO Repair or replace it. Harness Connector Inspection.
Then go to Step 11.

STEP 5. Check harness connector B-21 at ECM [M/T] or PCM [A/T] for damage.





Q. Is the harness connector in good condition?

YES Go to Step 6.

NO Repair or replace it. Harness Connector Inspection.
Then go to Step 11.

STEP 6. Measure the sensor output voltage at ECM [M/T] or PCM [A/T] connector B-21 by using power plant ECU check harness special tool MB991923.









(1)Disconnect all ECM [M/T] connectors or PCM [A/T] connectors.
Connect the power plant ECU check harness special tool MB991923 between the separated connectors.
(2)Turn the ignition switch to the "ON" position.





(3)Measure the voltage between terminal No. 108 and ground.

- When the engine is revved, voltage should be increase in response to revving.

Q. Is the measured voltage normal?

YES Go to Step 9.

NO Go to Step 7.

STEP 7. Check for open circuit or short circuit to ground between mass airflow sensor connector B-09 (terminal No. 3) and ECM [M/T] or PCM [A/T] connector B-21
(terminal No. 108).









Q. Is the harness wire in good condition?

YES Replace the mass airflow sensor. Then go to Step 8.

NO Repair it. Then go to Step 11.

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 23 Monitors, Trips, Drive Cycles and Readiness Codes.
(3)Check the diagnostic trouble code (DTC).

Q. Is DTC P0102 set?

YES Replace the ECM or the PCM. When the ECM or the PCM is replaced, register the encrypted code. Immobilizer System.
Then go to Step 11.

NO The inspection is complete.

STEP 9. Check harness connector B-21 at ECM [M/T] or PCM [A/T]
for damage.





Q. Is the harness connector in good condition?

YES Go to Step 10.

NO Repair or replace it. Harness Connector Inspection.
Then go to Step 10.

STEP 10. 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 1,620 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. How to Cope With Intermittent Malfunctions.

NO Replace the ECM or the PCM. When the ECM or the PCM is replaced, register the encrypted code. Immobilizer System.
Then go to Step 11.

STEP 11. 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 23 Monitors, Trips, Drive Cycles and Readiness Codes.

(2)Check the diagnostic trouble code (DTC).

Q. Is DTC P0102 set?

YES Retry the troubleshooting.
NO The inspection is complete.