Hot Wire MAF Sensor
A mass airflow sensor design that uses an electrically heated wire to measure intake air mass based on cooling effect.
A hot-wire MAF (Mass Airflow) sensor is a electronic sensor located in the engine's air intake duct that measures the mass of air entering the engine. It utilizes an electrically heated platinum wire suspended in the intake airstream, which is kept at a constant temperature above the ambient air temperature.
As air flows past the hot wire, it cools it down. The sensor's electronic circuit increases the electrical current flowing through the wire to maintain its constant hot temperature. The amount of current required to keep the wire hot is directly proportional to the mass of air flowing past it. The ECU reads this voltage signal to calculate engine load and inject the correct amount of fuel.
A dirty hot-wire MAF sensor can cause rough idling, engine hesitation under load, poor fuel economy, and lean fuel mixture codes. Dust or oil film from the air filter acts as an insulator, reducing the cooling effect and causing the sensor to under-report the air mass. Cleaning the wire using a dedicated MAF sensor cleaner spray restores correct voltage readings and engine performance.