Stock HFM/Mass Air Sensor, Pierburg - E34 525i M50, E34 530i M60, E36 325i/M3 OBD1

This part is listed by BMW as BMW part number 13621747155 (13 62 1 747 155) and is described as the HFM (Mass Air Sensor) for 1992-1995 E36 325i/M3, 1991-1995 E34 525i, and 1993-1995 E34 530i. It can also be used on any other M50/M52/S50/S52 that has been fully converted to OBD1 wiring harness and electronics (such as an engine swap).

This is a replacement sensor insert (it screws into the original tube-shaped stock HFM assembly) and replaces the sensitive electronic portion of the sensor. If your stock HFM looks OK (no obvious signs of cracks or breakage) this Pierburg unit simply replaces the failed internal "guts" of the sensor, and restores the air flow readings and calibration of of your BMW's very sensitive engine management system. 

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.

This is an OE HFM manufactured by Pierburg - the original supplier to BMW for many many parts and electrical components on BMWs. As an OE manufacturer (OEM) it meets all of BMW's original design, fitment, and performance requirements and is TUV approved. OEM parts are the best alternative to more expensive Original BMW parts because they are virtually identical without the inflated price tag. This part has a two year warranty.

This replaces BMW part number 13621747155 (13 62 1 747 155) as well as the older / obsolete part number 13621468624 (13 62 1 468 624). 

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