Click here to order! The BMW E46 digital engine management (DME) systems use a hot-film mass airflow sensor, installed between the air filter housing and the intake manifold, to monitor air flow into the engine intake. Inside the sensor, there is a thin metal film, which is maintained at a constant temperature via electrical current from the ECM. As ambient air flows over the film, it is cooled down and additional current is needed to maintain its constant temperature. The ECM monitors this additional current to determine the mass of the incoming air and to adjust fuel supply accordingly. Note: as the temperature of ambient air increases its volume expands. Since the airflow sensor hot film monitors the temperature of the passing air, it automatically adjusts for the increased volume (= lower density) of the incoming air.Mass air flow sensors accuracy skews over time and can lead to fault codes or drivability problems. When replacing, inspect the plastic intake air ducts for cracks or dry rot.

If the intake air ducts are faulty, replace them first and see if the problem you are having is remedied. aerus air purifier reviews pricesAn unmetered air leak downstream of the mass airflow sensor will set codes similar to a faulty mass airflow sensor. honeywell air purifier malaysia distributorWhen you suspect a mass airflow sensor as the culprit for setting a fuel trim fault code, check when the fault code was set. ridgid jobsite air cleanerYou can do this using OBD II freeze frame data. Normally, a vacuum leak would set a fuel trim fault code at idle or very low engine RPMs. A mass airflow meter would usually set a fault code when you are driving, or at a higher RPM. You can check your fault code freeze frame data using an OBD II scan tool, similar to how you would check for fault codes. 

In this tech article I will show you how to replace the mass airflow sensor on the BMW E46.Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches. Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you are working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability. Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article?

Leave a comment below. When leaving a comment, please leave your vehicle information. Remove the air filter housing assembly fasteners (yellow arrows) and disconnect the air flow meter electrical connector (green arrow). Loosen the air flow meter clamp (green arrow), then disconnect the duct from the air flow meter and remove the air filter housing from your engine compartment. Place the air filter housing on a workbench and disconnect the mass air flow sensor retaining tabs on both sides of the sensor by pulling them off. Be careful not to lose the clips: they have a tendency to pop off and hide. Pull the mass air flow sensor out of the E46 air filter housing. Check that the o-ring is in good shape and not worn or swollen. Replace if needed (green arrow). Install the new mass air flow sensor into the air filter housing. If the o-ring gives you a hard time going in, apply a small amount of dish soap to the o-ring, it will slide right in and the soap will not damage your o-ring.

Install the air filter housing into vehicle in reverse order of removal. Take vehicle for a test drive and then recheck your intake air duct connections. View Cart & CheckOut |  Recommend this page to a friend... Copyright © Pelican Parts Inc. IP address: 54.185.90.240Time: 2016-09-24T14:02:13ZURL: http://www.youtube.be/watch%3Fv%3DJ8Kp8qyDIfU%26feature%3Drelated IP address: 54.184.181.23Time: 2016-09-24T14:02:14ZURL: http://www.youtube.be/watch%3Fv%3DwwnIV1iYw4I Sold by PartUSA and Fulfilled by Amazon. MNJWS New MAF Mass Air Flow Sensor Meter for BMW 99-06 2.5L 2.8L 323 325 328 5WK9605DetailsBMW Genuine Intake Boot for 320i 323Ci 323i 325Ci 325i 325xi 328Ci 328i Z3 2.5 Z3 2.5i Z3 2.8 Air Mass Meter to Throttle Body Intake Boot E46 R38 E39 Z3 323i 328i 325i 5.1 x 4.9 x 4.4 inches #18,026 in Automotive (See top 100) #8 in Automotive > Replacement Parts > Sensors > Mass Air Flow #8 in Automotive > Replacement Parts > Sensors > Air Mass

See all 76 customer reviews As I drove along my engine light would come on telling me there was a problem. Being a dedicated BMW owner I took it into my mechanic and he said it was the mass air flow meter in my induction system. After he told me that the cost to replace it would be over $350.00, I thought I would do a little research myself and see if I could do it. When I was much younger I used to be very involved in auto mechanics so I thought I could handle this. To my surprise when I did a google search, I ended up on Amazon and found the exact item I needed at only about $65.00. Boy was I surprised! After receiving the item and looking at the manual for the car, I found out the install is something most anyone could do. You only need a flathead screwdriver and it take all of 5 minuets. It has been about a month and it is working flawlessly. My engine light does not come on anymore either. BMW 320i / 323i / 328i /325i / 325xi Sedan (3 Series - E46) New Mass Air Flow Meter (MAF 13621432356 / 5WK9605 / 5WK9608 / 5WK9626 / 28164-37100 / OK5581321 / 8ET009142-021)