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 Infiniti M45FACTORY OEM SERVICE PROCEDURE
Mass Air Flow Sensor
- Reconnect all harness connectors disconnected.
- Start engine and warm it up to normal operating temperature.
- Check voltage between ECM terminal 91 (Mass air flow sensor signal) and ground.
- If the voltage is out of specification, proceed the following.
- Turn ignition switch OFF.
- Disconnect mass air flow sensor harness connector and reconnect it again.
- Perform steps 2 and 3 again.
- If NG, remove mass air flow sensor from air duct. Check hot film for damage or dust.
- If NG, clean or replace mass air flow sensor.
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.