Atmospheric Pressure Sensor

Connect voltmeter to terminal D. Turn ignition on and note voltage. See Fig 1 .
Voltage at sea level should be 3.5-4.5 volts. Voltage at 6500 feet should be 2.5-3.5 volts. Replace if not to specification.

Fig 1: Atmospheric Pressure Sensor Connector Identification

Courtesy of MAZDA MOTORS CORP.