Subpar Exhaust Sound on BMW M4 Models Could Be Due to a Missing Resistor

BMW M4 Exhaust Tips 1 photo
Photo: BMW
If you were paying attention to the whole BMW M4 exhaust debate online, you couldn’t have noticed that there were basically two sides going at it. There were the guys saying that the new model sounds awesome and there were the ones claiming that it’s dreadful. Such situations have happened in the past but most of the time they were referring to different cars, not the same one.
Sure, not everyone has the same taste but something wasn’t right in the huge difference people noticed between cars. And now, we might have an explanation that has a lot to do with the electronics that control the valves in the rear mufflers.

TSB campaign 10061130400 - CAN Terminator

BMW issued an official Service Bulletin Announcement to install a missing CAN terminating resistor on all F82 M4 models built between March 2014 and July 2014. Apparently, this missing resistor messes with the way the DCT works and the sound of the exhaust system.

Apparently, "the general electrical system functions fail to operate properly" according to BMW, because of this missing part. How something like this could’ve happened in the first place, beats us, but there’s no point in splitting hairs now.

Your local dealership will install the missing resistor free of charge. The process requires a technician to remove the rear passenger side seat and access the wiring harnesses and install the new part. It shouldn’t take more than an hour.

Check you car's B-Pillar first

However, not all cars have to be taken back to dealerships. Owners should check to see if a Service Action label with the code 703 punched in is attached to the lower side of the B-Pillar. If you have this code on your car it means that this procedure was already done and you need not worry about it anymore. Hopefully, this will end a lot of disputes in the near future. If you’re one of the owners that took his/her M4 back to the shop, let us know how the different the car is right now.
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