13A-DTC P0102: Mass Airflow Circuit Low Input

DTC P0102: Mass Airflow Circuit Low Input

CIRCUIT OPERATION

The mass airflow sensor power is supplied from the MFI relay, and the ground is provided on the ECM terminal AFSE.
Sensor reference voltage (5-volt voltage) is applied to the mass airflow sensor terminal from the ECM terminal AFS5.
A voltage that is according to the mass airflow rate is sent to the ECM terminal AFS from the mass airflow sensor output terminal.

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

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.

Judgment Criterion

Mass airflow sensor output voltage has continued to be lower than 0.2 volt (corresponding to an air flow rate of 0 g/sec) for 2 seconds.

FAIL-SAFE AND BACKUP FUNCTION

Fuel control is carried out using throttle opening degree and engine speed in accordance with preset map.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 23 .

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

Mass airflow sensor failed.
Open or shorted mass airflow sensor circuit, or connector damage.
ECM failed.

DIAGNOSIS

Required Special Tools:

MB992744: Vehicle Communication Interface-Lite (V.C.I.-Lite)
MB992745: V.C.I.-Lite Main Harness A
MB992747: V.C.I.-Lite USB Cable Short
MB992748: V.C.I.-Lite USB Cable Long
MB991958: Scan Tool (M.U.T.-III Sub Assembly)

MB991824: Vehicles Communication Interface (V.C.I.)
MB991827: M.U.T.-III USB Cable
MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

MB992110: Power Plant ECU Check Harness

STEP 1. Using scan tool (M.U.T.-III), check data list item 10: Mass Airflow Sensor.

caution

To prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).

(1) Connect scan tool (M.U.T.-III) to the data link connector.

(2) Start the engine and run at idle.

(3) Set scan tool (M.U.T.-III) 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 700 and 1,100 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.

Is the sensor operating properly?

It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions

Go to Step 2.

STEP 2. Measure the power supply voltage at mass airflow sensor harness side connector.

(1) Disconnect the mass airflow sensor connector and measure at the harness side.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal power supply line and ground.

Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Is battery positive voltage (approximately 12 volts) present?

Go to Step 3.

Repair or replace the connector(s), or check and repair the harness of short to ground and open circuit in power supply line between MFI relay connector and mass airflow sensor connector. Then go to Step 9.

STEP 3. Measure the sensor voltage at mass airflow sensor harness side connector.

(1) Disconnect the mass airflow sensor connector and measure at the harness side.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal AFS5 line and ground.

Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Is battery positive voltage (approximately 12 volts) present?

Go to Step 5

Go to Step 4

STEP 4. Check of open circuit and short circuit to ground in AFS5 line between mass airflow sensor connector and ECM connector.

Is the harness wire in good condition?

Replace the ECM (Refer to, Removal and Installation

). Then go to Step 9.

Repair the connector(s) or wiring harness. Then go to Step 9.

STEP 5. Measure the sensor output voltage at ECM connector by using power plant ECU check harness special tool MB992110.

(1) Disconnect all ECM connectors. Connect the power plant ECU check harness special tool MB992110 between the separated connectors.

(2) Start the engine.

(3) Measure the voltage between terminal AFS line and ground.

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

Is the measured voltage normal?

Go to Step 8.

Go to Step 6.

STEP 6. Check of short to ground and open circuit in AFS line between mass airflow sensor connector and ECM connector.

Is the harness wire in good condition?

Go to Step 7.

Repair the connector(s) or wiring harness. Then go to Step 9.

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 23

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

Is DTC P0102 stored?

Replace the ECM (Refer to Removal and Installation

). Then go to Step 9.

The inspection is complete.

STEP 8. Using scan tool (M.U.T.-III), check data list item 10: Mass Airflow Sensor.

(1) Start the engine and run at idle.

(2) Set scan tool (M.U.T.-III) to the data reading mode for item 10, Mass Airflow Sensor.

(3) 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 700 and 1,100 millivolts.
When the engine is revved, the mass airflow rate should increase according to the increase in engine speed.

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Is the sensor operating properly?

It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions

Replace the ECM (Refer to Removal and Installation

). Then go to Step 9.

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 23

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

Is DTC P0102 stored?

Retry the troubleshooting.

The inspection is complete.