P0103

DTC P0103: Mass Airflow Circuit High Input


















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

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

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

- Mass airflow sensor output voltage is more than 4.9 V (corresponding to an air flow rate of 387 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 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 mass airflow sensor circuit, or connector damage.

- ECM failed.

DIAGNOSIS

Required Special Tool:

- 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 mV.

- When the engine is revved, the output voltage 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 A-05 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 8.
STEP 3. Check the continuity at mass airflow sensor harness side connector A-05.





(1)Disconnect the connector A-05 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 7.

NO Go to Step 4.

STEP 4. Check harness connector B-109 at ECM for damage.

Q. Is the harness connector in good condition?

YES Go to Step 5.
NO Repair or replace it. Harness Connector Inspection.
Then go to Step 8.
STEP 5. Check for open circuit between mass airflow sensor connector A-05 (terminal No. 4) and ECM connector B-109 (terminal No. 88).

Q. Is the harness wire in good condition?

YES Go to Step 6.
NO Repair it. Then go to Step 8.
STEP 6. Using scan tool MB991958, check data list item 10: Mass Airflow Sensor.

(1)Start the engine and run at idle.

(2)Set scan tool MB991958 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 1,300 and 1,650 mV.

- When the engine is revved, the output voltage should increase according to the increase in engine speed.

(4)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 (Refer to, Removal and Installation Removal and Replacement).
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 23 Monitors, Trips, Drive Cycles and Readiness Codes.

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

Q. Is DTC P0103 set?

YES Replace the ECM (Refer to, Removal and Installation Removal and Replacement).
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 23 Monitors, Trips, Drive Cycles and Readiness Codes.

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

Q. Is DTC P0103 set?

YES Retry the troubleshooting.
NO The inspection is complete.