Circuit/System Description

WARNING: This page is about a different variant/trim than selected.

Component	Description
B65 Intake Manifold Pressure and Air Temperature Sensor	The intake air temperature sensor 3 and the intake manifold pressure sensor are integrated in the same housing, which is located behind the throttle body.
B75C Multifunction Intake Air Sensor	The assembly has several functions: The mass air flow sensor is a hot film type sensor that measures the mass of air (not the volume) entering the engine. The signal varies with engine load and is displayed by the scan tool in Hertz (Hz) and grams per second (g/s). The intake air humidity sensor uses the same signal circuit as the intake air temperature sensor 2. The intake air humidity sensor modulates the pulse width of the signal. The intake air temperature sensor 2 modulates the frequency of the signal. That means the signal is both, PWM and FM modulated. The barometric pressure sensor generates an analog voltage that is proportional to the ambient air pressure. The intake air temperature sensor 1 varies its resistance depending on the temperature. Low temperature produces a high resistance: 126.8 kohms @ -60°C (-76°F) High temperature produces a low resistance: 62 ohms @ 150°C (302°F)
K20 Engine Control Module	The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly.
Q38 Throttle Body	The throttle body assembly contains 2 potentiometer-type throttle position sensors. When the throttle plate moves, the voltage of one sensor goes up and the voltage of the other sensor goes down. This redundant design enables the ECM to detect if the 2 signals indicate the same throttle plate position.

The ECM compares the measured mass air flow with the calculated air flow based on throttle position and the calculated air flow based on manifold absolute pressure.