Accord L4-2.2L SOHC VTEC (1994)
Barometric Pressure Sensor: Description and Operation
Barometric Pressure (BARO) Sensor Operation
PURPOSE
The Engine Control Module (ECM) uses the Barometric Sensor signal to sense changes in altitude so that ignition timing and fuel delivery can be
adjusted to maintain consistent engine performance.
OPERATION
The ECM supplies a 5 volt signal and a ground to the sensor. Changes in the pressure differential between the sealed cavity and the atmosphere
cause the silicon to flex. The flexing of the silicon generates a small voltage which is amplified by the support circuitry and used to modify the
fixed 5 volt signal supplied by the ECM. The modified signal is then returned to ECM.
CONSTRUCTION
The sensor consists of a silicon diaphragm and some support circuitry. The diaphragm covers a sealed cavity. The sensor is inside the ECM and
cannot be replaced separately
