DTC P0102: Mass Air Flow Circuit Low; DTC P0103: Mass Air Flow Circuit High [01/2019 - 03/2019]: Description
The mass air flow meter sub-assembly is a sensor that measures the intake air volume using the following built-in components:
- By-pass passage (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 over the temperature sensor (before heater), the heater, and then the temperature sensor (after heater) on the silicon chip sensor in the by-pass passage. As the intake air is warmed up when it is exposed to the heater, the temperature of the intake air flowing over the temperature sensor (after heater) is higher than that over 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 over 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 amount based on the pulse signal received from the mass air flow meter sub-assembly, and uses it to determine the fuel injection duration necessary for an optimal air-fuel ratio.
The heater control bridge circuit includes temperature sensors and power transistor, and maintains the heater temperature at a specific temperature.
HINT:
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.
| *a | Temperature Sensor (Before Heater) | *b | Temperature Sensor (After Heater) |
| *c | Heater | *d | Silicon Chip Sensor |
| *e | Air Flow | - | - |
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Memory |
|---|---|---|---|---|---|
| P0102 | Mass Air Flow Circuit Low | The mass air flow meter sub-assembly 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 sub-assembly output frequency is higher than 9.8 kHz for 3 seconds. (1 trip detection logic) |
|
Comes on | DTC stored |