Modern fuel injection systems depend on knowing the precise mass of air entering the engine at every moment, and the mass air flow sensor is the component that provides this measurement. Positioned in the intake tract between the air filter and the throttle body, it generates a voltage or frequency signal the ECU uses to calculate injector pulse width and ignition timing. When the sensor drifts out of calibration — a gradual process caused by oil contamination from a poorly maintained air filter or simple component ageing — the ECU starts working from incorrect data. The characteristic failure mode is an engine that idles roughly, hesitates under acceleration, or runs noticeably rich with black smoke at the exhaust. Fault codes P0100 to P0104 on a diagnostic scanner usually point directly to this sensor. Because the signal is used alongside readings from the oxygen sensor and throttle position sensor to trim fuelling, a faulty MAF can mask or mimic faults elsewhere in the fuel management system. The OE reference is model-specific — a Volkswagen TDI unit differs in housing geometry and signal range from a Mercedes-Benz petrol equivalent — making it important to match the number precisely. Bosch and Magneti Marelli supply a large share of original-equipment sensors in this catalogue.
Each sensor listed on this page is cross-referenced via TecDoc to a specific vehicle application. Confirm the match by checking the OE number printed on your existing unit — it is usually on a label on the sensor body — and comparing it to the references shown. Using your registration or VIN in the make-model-year selector filters results to your exact engine variant, which matters because the same model generation can use different sensor types across different engine codes.
OEM sensors from Bosch or Magneti Marelli are produced to the vehicle builder's original specification and carry the factory OE reference. Aftermarket alternatives from quality suppliers are manufactured to the same measurement tolerances and output characteristics, though some lesser-known brands use lower-grade sensing elements that can drift more quickly. Crucially, any replacement sensor must match the original signal type — hot-film and Karman-vortex sensors are not interchangeable even if the housing fits.
In some cases, contamination from oil mist or fine dust can be removed with dedicated MAF cleaner spray applied to the sensing element, temporarily restoring the signal. This is worth attempting before purchasing a replacement — the procedure takes minutes and costs very little. However, if the fault codes return within a few hundred miles, or if the sensing wire or film is physically damaged or discoloured, cleaning will not provide a lasting fix and replacement is the correct course.
The most common complaints are an unstable idle, a noticeable flat spot during light throttle acceleration, increased fuel consumption, and occasional black or sooty exhaust smoke caused by the ECU over-fuelling. The engine management light will typically illuminate with codes in the P0100–P0104 range. Some cars with a failing MAF will enter a limp-home mode that limits power to protect the drivetrain. Cold-start performance often degrades first because the sensing element struggles to provide accurate readings until it reaches operating temperature.
Showing 100 of 8,377 Mass Air Flow Sensor OE numbers. Enter the OE on the main OE search to jump to any reference.
