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.
2007 Mazda CX-9 V6-3.5LFACTORY OEM SERVICE PROCEDURE
Air Flow Meter/Sensor: Testing and Inspection
MASS AIR FLOW (MAF) SENSOR INSPECTION [MZI-3.5]
NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.
Visual Inspection
1. Verify the following items of the MAF sensor.
- Damage, cracks
- Rusted sensor terminal
- Bent sensor terminal
- If there is any malfunction, replace the MAF sensor.
Voltage Inspection
1. Remove the MAF sensor with the connector still connected.
2. Turn the ignition switch to the ON position.
3. Verify that the MAF sensor output voltage (M-MDS monitor item: MAF) changes when wind is introduced gradually to the sensor part of the MAF sensor.
- If it cannot be verified even though the related harnesses have no malfunction, replace the MAF sensor.
- If the monitor item status/specification (reference) is not within the specification, even though the resistance is within the specification, perform the "Circuit Open/Short Inspection".
Circuit Open/Short Inspection
1 Disconnect the PCM connector.
2. Disconnect the MAF/IAT sensor connector.
3. Inspect the following wiring harnesses for open or short. (Continuity inspection)
Open circuit
- If there is no continuity, the circuit is open. Repair or replace the wiring harness.
- MAF/IAT sensor terminal A and main relay No.1 terminal D
- MAF/IAT sensor terminal C and PCM terminal 1 AJ
- MAF/IAT sensor terminal D and PCM terminal 1 AN
- MAF/IAT sensor terminal E and PCM terminal 1 AL
Short circuit
- If there is continuity, the circuit is shorted. Repair or replace the wiring harness.
- MAF/IAT sensor terminal A and body ground
- MAF/IAT sensor terminal C and power supply
- MAF/IAT sensor terminal C and body ground
- MAF/IAT sensor terminal D and power supply
- MAF/IAT sensor terminal D and body ground
- MAF/IAT sensor terminal E and power supply
NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.
Visual Inspection
1. Verify the following items of the MAF sensor.
- Damage, cracks
- Rusted sensor terminal
- Bent sensor terminal
- If there is any malfunction, replace the MAF sensor.
Voltage Inspection
1. Remove the MAF sensor with the connector still connected.
2. Turn the ignition switch to the ON position.
3. Verify that the MAF sensor output voltage (M-MDS monitor item: MAF) changes when wind is introduced gradually to the sensor part of the MAF sensor.
- If it cannot be verified even though the related harnesses have no malfunction, replace the MAF sensor.
- If the monitor item status/specification (reference) is not within the specification, even though the resistance is within the specification, perform the "Circuit Open/Short Inspection".
Circuit Open/Short Inspection
Circuit Open/Short Inspection:
1 Disconnect the PCM connector.
2. Disconnect the MAF/IAT sensor connector.
3. Inspect the following wiring harnesses for open or short. (Continuity inspection)
Open circuit
- If there is no continuity, the circuit is open. Repair or replace the wiring harness.
- MAF/IAT sensor terminal A and main relay No.1 terminal D
- MAF/IAT sensor terminal C and PCM terminal 1 AJ
- MAF/IAT sensor terminal D and PCM terminal 1 AN
- MAF/IAT sensor terminal E and PCM terminal 1 AL
Short circuit
- If there is continuity, the circuit is shorted. Repair or replace the wiring harness.
- MAF/IAT sensor terminal A and body ground
- MAF/IAT sensor terminal C and power supply
- MAF/IAT sensor terminal C and body ground
- MAF/IAT sensor terminal D and power supply
- MAF/IAT sensor terminal D and body ground
- MAF/IAT sensor terminal E and power supply
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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