📖 What It Does
Gives the ECU the single most important number for fueling. Too little reading and the engine runs lean. Too much and it runs rich. Either causes drivability and emissions problems.
⚙ How It Works
A heated wire (or hot film) sits in the airstream. The ECU keeps the wire at a fixed temperature. As air flows past, the wire cools, and more current is needed to keep it hot. That current is the air-mass reading. The faster the air flows, the more current is needed.
⚠ Symptoms When It Fails
Symptoms include rough idle, hesitation, stalling, poor fuel economy, P0100-P0103 codes, and lean/rich codes like P0171/P0174. Most "failed" MAF sensors are just contaminated with oil from an over-oiled aftermarket air filter or dust from a torn factory filter. See full symptom guide.
💰 Replacement Cost
Replacement: $150–$400. An OEM sensor is $80–$250. Labor is 15 minutes. Try cleaning first - it works most of the time. See MAF cost.