Alternator Bosch or Motorcraft

If you can get motorcraft, that is my recommendation.

I've got the flickering lights so I'm going between the Denso reman and Bosch reman. Looks like the Bosch reman is done in house and the germans have pretty good engineering imo.

I recently replaced my alternator on one car w/a new Bosch unit. Cost about $200 and took me a couple of hours. Dealer cost just for the part was $700 and with book time they priced it out at over $1,400.

Bosch Alternators have 2 posts on them, the big one is for main battery ground, the smaller one is for the exciter or blue wire. When the cars ignition switch is turned on, the Dash light (led and diode) applies 12V+ to the coils to excite them, so the alternator can produce a charge. When the Alternator is producing current and voltage it goes to 13.5-14Volts.

The part # for the Alternator (Automatic trans) is 6H903016L and it's made by Bosh. [Europaparts](https://parts.audiusa.com/p/Audi_2012_A4-Base-Sedan-20L-AT-Quattro/Alternator/48001649/06H903016L.html) sell's it for $499.95 (OEM).

I changed out my original Valeo alternator with a Bosch unit at 100k miles. Never had a problem with either one.

I replaced the battery, and upgraded to an AGM battery while I was at it. The problem still wasn’t solved though.

I order a Bosch AL113MX Reman Alternator (yep Bosch reman the Motorola) since that was what was currently in there. The 81 has a big square York compressor mounted right on top of the alternator which means that to get the rear alternator bolt you better have the right extensions and you are going to do it blind. So after at lot of effort I got the old alternator out and the new one in and only then did I notice that the pulley did not line up.

I when my original alternator failed in my 540i/6, the replacement rebuilt Bosch unit would produce 13.5-13.7v for a while after the car had warmed up, then would gradually fall to less than battery voltage. Running the A/C and revving the engine at stoplights would keep the battery light from flickering, but eventually, it would show full symptoms of a dead charging system.

It's a dice roll. I've had some success with them, but when I put a reman one in my Focus, it only lasted 2 weeks.