Mechanic Glossary

Mass Airflow Sensor

An electronic sensor in the intake tract that measures the mass of air entering the engine, allowing the ECU to calculate the correct fuel injection volume.

The Mass Airflow (MAF) sensor is critical for engine efficiency. Located in the intake pipe between the air filter box and the throttle body, it measures the weight of the incoming air. The sensor houses a heated platinum wire. As air passes through, it cools the wire. The sensor increases electrical current to keep the wire at a constant temperature. The computer measures this current change to calculate the exact mass of air entering the engine, adjusting the fuel injector spray to match.

MAF sensors are sensitive. Dirt, oil from reusable filters, and carbon can coat the wire, insulating it and distorting the readings. The engine will run rich or lean, causing rough idling, hesitation during acceleration, stalling, and check engine light codes (like P0101).

Frequently Asked Questions

Remove the sensor from the intake pipe and spray the internal wire with a specialized MAF sensor cleaner. Let it air dry completely before reinstallation. Never touch the wire with a brush, cotton swab, or your fingers, as the wire is fragile and will break.
Engine stalling, hesitation or stumbling when you step on the gas, poor fuel economy, black smoke from the exhaust, and a check engine light.
Yes. A cheap or torn air filter lets dirt and grit enter the intake, which hits and coats the MAF sensing wire. Over-oiling a reusable cotton filter will also coat the wire in oil.
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