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
Air Flow Meter/Sensor: Testing and Inspection
MASS AIR FLOW (MAF) SENSOR INSPECTION
NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.
Visual Inspection
1. Visually inspect the MAF sensor for the following:
- Damage, cracks
- Rusted sensor terminal
- Bent sensor terminal
- If there is any malfunction, replace the MAF sensor.
- If the monitor item status/specification (reference) is not within the specification even though there is no malfunction, perform the "Circuit Open/Short Inspection".
Voltage Inspection
1. Remove the MAF/IAT sensor without disconnect the MAF/IAT sensor connector.
2. Turn the ignition switch to the ON position.
3. As the air gradually approaches the MAF detection part of the MAF/IAT sensor, verify that the voltage at PCM terminal 1AC (WDS PID: MAF) varies.
- If it cannot be verified even though the related harnesses have no malfunction, replace the MAF/IAT sensor. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [LF], INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [L3].)
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Disconnect the MAF sensor connector.
3. Inspect the following wiring harnesses 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.
- MAF sensor terminal A and main relay terminal E
- MAF sensor terminal B and PCM terminal 1BD
- MAF sensor terminal C and PCM terminal 1AC
Short circuit
- If there is continuity, there is a short circuit. Repair or replace the wiring harness.
- MAF sensor terminal A and body GND
- MAF sensor terminal C and power supply
- MAF sensor terminal C and body GND
- MAF sensor terminal B and power supply
NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.
Visual Inspection
1. Visually inspect the MAF sensor for the following:
- Damage, cracks
- Rusted sensor terminal
- Bent sensor terminal
- If there is any malfunction, replace the MAF sensor.
- If the monitor item status/specification (reference) is not within the specification even though there is no malfunction, perform the "Circuit Open/Short Inspection".
Voltage Inspection
1. Remove the MAF/IAT sensor without disconnect the MAF/IAT sensor connector.
2. Turn the ignition switch to the ON position.
3. As the air gradually approaches the MAF detection part of the MAF/IAT sensor, verify that the voltage at PCM terminal 1AC (WDS PID: MAF) varies.
- If it cannot be verified even though the related harnesses have no malfunction, replace the MAF/IAT sensor. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [LF], INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [L3].)
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Disconnect the MAF sensor connector.
3. Inspect the following wiring harnesses 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.
- MAF sensor terminal A and main relay terminal E
- MAF sensor terminal B and PCM terminal 1BD
- MAF sensor terminal C and PCM terminal 1AC
Short circuit
- If there is continuity, there is a short circuit. Repair or replace the wiring harness.
- MAF sensor terminal A and body GND
- MAF sensor terminal C and power supply
- MAF sensor terminal C and body GND
- MAF sensor terminal B and power supply
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
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.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.