Catera V6-3.0L VIN R (1997)
Mass Air Flow (MAF) Sensor: Description and Operation
Mass Air Flow Sensor
Description
The Mass Air Flow (MAF) sensor measures the amount of air that is ingested by the engine. The direct measurement of the air entering the engine is
more accurate than the calculating air/flow from the other sensor inputs. The MAF sensor has a switched battery feed, a ground, a signal circuit and a
signal return circuit.
Construction
The MAF sensor that is used on this vehicle is a hot film type and is used in order to measure the air flow rate. The MAF output voltage is a function of
the power that is required in order to keep the air flow sensing elements at a fixed temperature above the ambient temperature.
Operation
The air flowing through the sensor cools the sensing elements. The amount of cooling is proportional to the amount of air flow. As the air flow increases,
a greater amount of current is required in order to maintain the hot film at a constant temperature. The MAF sensor converts the changes in the current
draw to a voltage signal that is read by the ECM. The ECM calculates the air flow based on this signal.
ECM Diagnostics
The ECM monitors the MAF sensor signal voltage and can determine if the sensor signal voltage is too low, too high, not indicating the expected airflow
for a given operating condition, or that the signal appears to be stuck based on the lack of normal signal fluctuations that are expected during the engine
operation. When the ECM detects a malfunction in the MAF sensor circuit, the following DTC(s) will set:
^
DTC P0100 - MAF Sensor Circuit
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DTC P0101 - MAF Sensor Circuit Performance
Scan Tool Diagnostics
The scan tool reads the MAF value and displays the value in grams per second (gm/s). Values should change rather quickly on acceleration, but should
remain fairly stable at any given RPM.