Hi,

I've just gotten this 2001 BMW 540i and know it has been in good shape and has been taken good care of before I purchased it. (It has about 64,000 miles and a V8 engine.) But for the last few weeks, tons of things have gone wrong and I've spent over $2,000 in repairs. I've had the oil level sensor replaced, the engine-cooling thermostat replaced (that, at least, was under a parts warranty), one of the oxygen sensors replaced, and the alternator and battery replaced. It has been devastating.

One of the repair trips was to the dealer, and they recommended that my mass air flow sensor needed to be replaced, but there were numerous problems with my visit there and I felt that they weren't being straightforward with me, so I had minimal work done there and took it to my own mechanic, who didn't think the MAF sensor needed to be replaced.

Yesterday, I got in the car and none of the gauges on the car would work. The electrical system seemed shot, as the blinkers wouldn't work properly, the digital clock on the dash had stopped, the air conditioner was pulsing, etc. So I brought the car home and am trying to figure out what to do next. Does this sound like a problem with the mass air flow sensor? If so, how much does this typically cost to replace? Are there other likely causes for these symptoms?

Thank you very much for any ideas!

what this sounds like is the ignition switch is causing
multiple problems. and perhaps a fan motor final stage.
the ignition switch part # 61-32-6-901-962 for automatics and 61-32-5-901-961 for manual transmission
if the fan motor runs erratically or changes speed
on its own the final stage part # is 64-11-8-385-549
the mass air flow sensor may need replacement, and without more information, I cannot recommend it be replaced, however there is a bulletin regarding this issue.
repost if needed and keep in touch.

Your suggestion makes sense, as I forgot to mention that my engine was also making a loud noise. It sounds like it could be something to do with the fan or a part in the front of the engine. It just seemed so strange, as it was actually driving perfectly, and then all at once it was making a loud noise and all of the interior electrical gear was going haywire.

I don't suppose you have any idea whether this is a tremendously expensive thing to fix... ?

Thank you again for your advice.

now this sounds like an alternator issue