Car Sensors Guide: MAF, MAP and O2 (Lambda)

A modern engine relies on a set of sensors to hit the right air/fuel mixture. The three most critical are the MAF, MAP and oxygen (lambda) sensors.

MAF (Mass Air Flow)

Measures the amount of air entering the engine. When dirty or faulty, the engine runs lean/rich; you get codes like P0101 and power loss. It can often be cleaned with a dedicated cleaner.

MAP (Manifold Absolute Pressure)

Measures the pressure (vacuum/load) in the intake manifold. A fault causes power loss and codes P0106–P0108. Vacuum leaks corrupt this sensor's reading.

O2 / Lambda Sensor

Measures oxygen in the exhaust to report whether the mixture is rich or lean. The upstream sensor adjusts the mixture; the downstream one monitors the catalyst. When aged, fuel use rises and codes like P0130–P0141 and P0420 appear.

Shared symptoms

• Increased fuel consumption
• Rough idle and power loss
• Check-engine light
• Failed emissions test

AutoMulti shows these sensors' live values and flags anomalies, so you notice early which sensor is the problem.