Mass Air Flow And Temperature Sensor
There are 2 Mass Air Flow and Temperature (MAFT) sensors installed to the vehicle, 1 in each air filter housing. The MAFT sensors allow the Powertrain Control Module (PCM) to measure the mass flow and the temperature of the air flow into the engine. The mass air flow is used to determine the fuel quantity to be injected in order to maintain the target air/fuel mixture required for correct operation of the engine and the catalytic converters.
The mass air flow is measured with a hot film element in the sensor. The temperature of the air flow is measured with a Negative Temperature Coefficient (NTC) thermistor in the sensor. A 5 pin electrical connector on each MAFT sensor provides the interface with the engine wiring harness.
If the hot film element signal fails, the PCM invokes a software backup strategy to calculate the mass air flow from other inputs. Closed loop fuel control, closed loop idle speed control and evaporative emissions control are suspended. The engine will suffer from poor starting, poor throttle response and, if the failure occurs while driving, the engine speed may dip and surging may occur before recovering.
If the NTC thermistor signal fails the PCM adopts a default value of 25°C (77°F) for the intake air temperature.