Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2004 Mazda 3 L4-2.0LFACTORY OEM SERVICE PROCEDURE
Barometric Pressure Sensor: Testing and Inspection
BAROMETRIC PRESSURE (BARO) SENSOR INSPECTION
NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.
Voltage Inspection
1. Remove the BARO sensor with the connector still connected.
2. Turn the ignition switch to the ON position.
3. Verify that the voltage at PCM terminal 1AG (WDS PID: BARO) is within the specification.
- If not within the specification even though the related wiring harnesses have no malfunction, replace the BARO sensor.
BARO sensor output voltage
2.3 - 4.7 V
4. Disconnect the BARO sensor hose.
5. Install a vacuum pump to the BARO sensor.
6. Apply a vacuum of 30 kPa {225 mmHg, 8.86 inHg} to the BARO sensor and verify that change in voltage at PCM terminal 1AG (WDS PID: BARO) is within the specification.
- If not within the specification, replace the BARO sensor.
BARO sensor output voltage variance
0.97 - 1.41 V
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Inspect the following wiring harness for an open or short circuit. (Continuity inspection)
Open circuit
- If there is no continuity, there is an open circuit. Repair or replace the wiring harness.
- Barometric pressure sensor terminal A and PCM terminal 1AG
- Barometric pressure sensor terminal B and PCM terminal 1AA
- Barometric pressure sensor terminal C and PCM terminal 1AE
Short circuit
- If there is continuity, there is a short circuit. Repair or replace the wiring harness.
- Barometric pressure sensor terminal C and power supply.
- Barometric pressure sensor terminal C and body GND.
- Barometric pressure sensor terminal A and power supply.
- Barometric pressure sensor terminal A and body GND
NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.
Voltage Inspection
1. Remove the BARO sensor with the connector still connected.
2. Turn the ignition switch to the ON position.
3. Verify that the voltage at PCM terminal 1AG (WDS PID: BARO) is within the specification.
- If not within the specification even though the related wiring harnesses have no malfunction, replace the BARO sensor.
BARO sensor output voltage
2.3 - 4.7 V
4. Disconnect the BARO sensor hose.
5. Install a vacuum pump to the BARO sensor.
6. Apply a vacuum of 30 kPa {225 mmHg, 8.86 inHg} to the BARO sensor and verify that change in voltage at PCM terminal 1AG (WDS PID: BARO) is within the specification.
- If not within the specification, replace the BARO sensor.
BARO sensor output voltage variance
0.97 - 1.41 V
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Inspect the following wiring harness for an open or short circuit. (Continuity inspection)
Open circuit
- If there is no continuity, there is an open circuit. Repair or replace the wiring harness.
- Barometric pressure sensor terminal A and PCM terminal 1AG
- Barometric pressure sensor terminal B and PCM terminal 1AA
- Barometric pressure sensor terminal C and PCM terminal 1AE
Short circuit
- If there is continuity, there is a short circuit. Repair or replace the wiring harness.
- Barometric pressure sensor terminal C and power supply.
- Barometric pressure sensor terminal C and body GND.
- Barometric pressure sensor terminal A and power supply.
- Barometric pressure sensor terminal A and body GND
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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