Audi A4 Mass Air Flow Sensor

A MAF sensor measures incoming air mass flow; a MAP sensor measures pressure in the intake manifold. The engine computer uses their signals differently, so the two are not interchangeable replacement parts.

A sensor-only replacement can be appropriate when the existing housing is sound and the application specifies that configuration. If the flow tube is cracked or the original design requires a complete assembly, choose the appropriate housing-included part.

The electrical connection and signal design must match the vehicle. The A-Premium range includes different three- and five-terminal examples; neither the terminal count nor a similar shape alone establishes interchangeability.

A code identifies a circuit or performance concern, not necessarily a failed sensor. Wiring, connections and intake leaks can affect diagnosis; checking the live signal and the rest of the intake system helps locate the cause.

The sensing element is delicate and can be damaged by contact. Handle the sensor by its housing or connector and follow the part manufacturer's instructions for inspection or cleaning; do not scrape or touch the element.