DTC Code | DTC Name |
---|---|
P0102 | Mass Air Flow Circuit Low |
P0103 | Mass Air Flow Circuit High |
DESCRIPTION
The mass air flow meter is a sensor that measures the intake air volume using the following built-in components:
By-pass duct (allows some of the intake air to flow past a silicon chip sensor)
Silicon chip sensor (uses a heater control bridge circuit and temperature sensor bridge circuit to detect the difference in the temperature of the intake air that passes the sensors positioned before and after the heater).
Control circuit (converts the difference in temperature into a pulse signal and performs correction)
Intake air flows past the temperature sensor (before heater), the heater, and then the temperature sensor (after heater) of the silicon chip sensor in the by-pass duct. As the intake air is warmed up when it is exposed to the heater, the temperature of the intake air as it flows past the temperature sensor (after heater) is higher than when it flows past the temperature sensor (before heater). The difference in temperature of the intake air at each temperature sensor varies depending on the velocity of the intake air that flows past the silicon chip sensor. The temperature sensor bridge circuit detects the difference in temperature and the control circuit converts it into a pulse signal and outputs it to the ECM. When the temperature detected by the temperature sensor (before heater) is higher than that detected by the temperature sensor (after heater), backflow of the intake air is detected.
The ECM calculates the intake air volume based on the pulse signal received from the mass air flow meter, and uses it to determine the fuel injection duration necessary for an optimal air-fuel ratio.
The heater control bridge circuit has a temperature sensor and power transistor, and maintains the heater temperature at a specific temperature.
Tech Tips
When DTCs is stored, the ECM enters fail-safe mode. During fail-safe mode, the ECM calculates the fuel injection duration based on the engine speed and throttle valve angle. Fail-safe mode continues until a pass condition is detected.
*1 | Mass Air Flow Meter | - | - |
*a | Silicon Chip Sensor | *b | By-pass Duct |
*c | Heater | *d | Heater Thermistor |
*e | Intake Air | *f | Temperature Sensor (After Heater) |
*g | Temperature Sensor (Before Heater) | *h | Intake Air Thermistor 1 |
*i | Intake Air Thermistor 2 | *j | Temperature Sensor (Before Heater) 1 |
*k | Temperature Sensor (After Heater) 2 | *l | Temperature Sensor (After Heater) 1 |
*m | Temperature Sensor (Before Heater) 2 | *n | Control Circuit |
*o | Heater Control Bridge Circuit | *p | Temperature Sensor Bridge Circuit |
*q | Air Flow | - | - |
DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Memory |
---|---|---|---|---|---|
P0102 | Mass Air Flow Circuit Low | The mass air flow meter output frequency is less than 0.1 kHz for 3 seconds (1 trip detection logic) |
|
Comes on | DTC stored |
P0103 | Mass Air Flow Circuit High | The mass air flow meter output frequency is higher than 9.8 kHz for 3 seconds. (1 trip detection logic) |
|
Comes on | DTC stored |
MONITOR DESCRIPTION
If there is a defect or an open or short circuit in the mass air flow meter, the frequency level deviates from the normal operating range. The ECM interprets this deviation as a malfunction in the mass air flow meter circuit and stores a DTC.
Example:
When the sensor output frequency remains less than 0.1 kHz, or higher than 9.8 kHz for 3 seconds, the ECM stores a DTC.
MONITOR STRATEGY
Frequency of Operation | Continuous |
CONFIRMATION DRIVING PATTERN
Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the engine switch off and wait for at least 30 seconds.
Turn the engine switch on (IG).
Turn the GTS on.
Wait 5 seconds or more.
Enter the following menus: Powertrain / Engine / Trouble Codes.
Turn the GTS on.
Read the pending DTCs.
Tech Tips
If a pending DTC is output, the system is malfunctioning.
If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine / Utility / All Readiness.
Input the DTC: P0102 or P0103.
Check the DTC judgment result.
GTS Display | Description |
---|---|
NORMAL |
|
ABNORMAL |
|
INCOMPLETE |
|
N/A |
|
Tech Tips
If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A, perform the Confirmation Driving Pattern and check the DTC judgment result again.
WIRING DIAGRAM
*a | VCVG |
*b | Mass Air Flow Meter |
CAUTION / NOTICE / HINT
Tech Tips
Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
CHECK TERMINAL VOLTAGE (POWER SOURCE OF MASS AIR FLOW METER)
*a | Front view of wire harness connector (to Mass Air Flow Meter) |
Disconnect the mass air flow meter.
Turn the engine switch on (IG).
Measure the voltage according to the value(s) in the table below.
Standard Voltage | |||||||||
---|---|---|---|---|---|---|---|---|---|
|
Result | |||
---|---|---|---|
|
NG |
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM) Click here |
OK |
REPLACE MASS AIR FLOW METER
Replace the mass air flow meter.
Result | ||
---|---|---|
|
NEXT |
CHECK IF DTC OUTPUT RECURS (SEE IF DTC P0102 AND P0103 ARE OUTPUT AGAIN)
Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Clear the DTCs.
Turn the engine switch off and wait for at least 30 seconds.
Turn the engine switch on (IG).
Turn the GTS on.
Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
Enter the following menus: Powertrain / Engine / Trouble Codes.
Read the DTCs.
Result | ||||||
---|---|---|---|---|---|---|
|
A |
REPLACE ECM Click here |
B |
END |
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
Disconnect the E38 mass air flow meter connector.
Disconnect the E1 ECM connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance | |||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Result | |||
---|---|---|---|
|
OK |
REPLACE ECM Click here |
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR |