Replace Voltage regulator or Alternator?

[gillara]

Hello all,

My 2009 e93 m3 with 49k miles has been acting funny. Three months ago my car began flashing a series of yellow lights while driving (ABS, Traction control, DSC, etc.), a transmission malfunction warning and finally not turning on.

I immediately had the car towed to my nearest BMW dealership and had a brand new battery installed per the technician's recommendation.

Fast forward to yesterday, the same problem occurred but this time the BMW technician is recommending that I replace the alternator.

I have been quoted $2000 to replace the alternator and I believe that I could do the repair on my own and while saving some money at the same time.

My question is does it make sense to replace the voltage regulator instead of the alternator?

Finally, if I do the job myself do I need to reregister the battery once I replace the voltage regulator or alternator?

Thanks

[ExcuseM3]

I just replaced my alternator and voltage regulator myself last week. I would just replace the entire thing since you're already in the engine. Everything together cost like $280 and I was able to do it myself in a couple hours following a diy on here.

[T!m3]

Originally Posted by gillara

Hello all,

My 2009 e93 m3 with 49k miles has been acting funny. Three months ago my car began flashing a series of yellow lights while driving (ABS, Traction control, DSC, etc.), a transmission malfunction warning and finally not turning on.

I immediately had the car towed to my nearest BMW dealership and had a brand new battery installed per the technician's recommendation.

Fast forward to yesterday, the same problem occurred but this time the BMW technician is recommending that I replace the alternator.

I have been quoted $2000 to replace the alternator and I believe that I could do the repair on my own and while saving some money at the same time.

My question is does it make sense to replace the voltage regulator instead of the alternator?

Finally, if I do the job myself do I need to reregister the battery once I replace the voltage regulator or alternator?

Thanks

I only replaced regulator and it worked. You need valeo 599221 regulator. The same as the oem one, just no bmw logo and it's cheap af.

[pbonsalb]

If the OP can, follow ExcuseM3’s example and DIY. It might take a first timer longer than a couple of hours but since an alternator with internal regulator included is under $300, paying someone $2000 to change it is something I would do only if I had no other choice. I changed mine a couple of years ago in a few hours. There are good DIY posted in this forum. The tap trick on the lower bolt helped.

One guy recently changed just the regulator and then had to go back and change the whole thing. He found not return the regulator so he spent more on parts. I would recommend against this if you are paying for labor. Not worth the risk of paying twice at the $400 per hour labor rates you seem to be paying.

[Ajolives]

$2k is outrageous, there are a couple DIYs out there. Replace the whole unit and be careful when removing the fan. The coolant reservoir return line outlet on the upper hose snaps easily if you're not patient (first-hand knowledge).

[RedScytheM3]

Originally Posted by gillara

Hello all,

My 2009 e93 m3 with 49k miles has been acting funny. Three months ago my car began flashing a series of yellow lights while driving (ABS, Traction control, DSC, etc.), a transmission malfunction warning and finally not turning on.

I immediately had the car towed to my nearest BMW dealership and had a brand new battery installed per the technician's recommendation.

Fast forward to yesterday, the same problem occurred but this time the BMW technician is recommending that I replace the alternator.

I have been quoted $2000 to replace the alternator and I believe that I could do the repair on my own and while saving some money at the same time.

My question is does it make sense to replace the voltage regulator instead of the alternator?

Finally, if I do the job myself do I need to reregister the battery once I replace the voltage regulator or alternator?

Thanks

Just replace the whole unit. I replaced my regulator first and the problem persisted. Then I replaced the alternator a few days later. It's not much more money and it is certainly the same amount of time to replace the alternator rather than just the regulator. Another problem is you cannot tell which component has failed until you take them out and at that point just pop the whole new unit in and be done with it. For me a bearing housing on the alternator cracked and replacing the regulator did nothing for it.