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 FX45FACTORY 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 51 (Mass air flow sensor signal) and ground.

Fig 1: Checking Voltage At ECM Connector Terminal 51
Courtesy of NISSAN MOTOR CO., U.S.A.

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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