HFM/Mass Air Sensor, BMW - E36 328i/M3, E39 528i 97-98 (M52, S52)

This part is listed by BMW as BMW part number 13621703275 (13-62-1-703-275) and is described as Genuine BMW HFM (Hot Film Mass Air Sensor) for 1996-1999 E36 323is/328i/M3 and 1997-1998 E39 528i.

This is the stock-sized HFM used for the above cars. Upgrades may also be available, depending on model.

The HFM (Hot Film Meter, or MAF) measures air density and temperature in the intake so the engine computer can make fuel adjustments on the fly. When it goes bad and no longer sends data the ECU will revert to a rich setting (more fuel) and eventually it will throw a fault code. If you're having drivability issues or MPG has dropped, remove the HFM and intake boots, clean with HFM cleaner, check for cracks in the boots, and reinstall. If problems persist it may be time for a new HFM.

In our view, a Genuine BMW HFM has stricter tolerances and better performance than any other brand of HFM. If performance and expectations are your most-valued consideration, our recommendation is a Genuine BMW airflow sensor. If price is a factor, look to the OEM and aftermarket brands.

This is a Genuine BMW HFM with a two year warranty. Buying a Genuine part will usually be more expensive than an OEM or aftermarket brand but you are assured that it meets BMW's designs for fitment, performance, and longevity. It will also be the very latest design, incorporating any updates or revisions that an aftermarket brand typically will ignore.

For full BMW fitment information or for assistance from one of our BMW experts, we recommend calling us at 877-639-9648.