About a week ago I purchased my first new-to-me vehicle, a 2012 Mini Copper S Countryman All4 from a used car dealership close-ish to where I live. Before buying the Mini I took the car for two test drives on different days; during the second test drive the car threw an engine code, I immediately told the dealership and they plugged it into their code reader. I was told someone must have accidentally filled the Mini with 87 octane instead of the recommended 91 or higher. I bought the car hoping that was all, filled the car with 91 as soon as I left the dealership and then a day after refilled what had been used and put a half bottle of octane booster in along with the new fuel, the light shortly went off after cycling through all of the 87.
Then a couple days ago I start to hear a new noise coming from the back end. A faint howling noise that pulsates in volume. The sound become noticeable when I’m getting up to speed, probably around 45-50mph and above. It sounds to me like whatever is making the noise is some rotating part in the rear transmission/axel/wheel assembly but I am new to the Mini brand and I’m not the most mechanically inclined. ANY HELP THAT CAN BE GIVING IN TROUBLE SHOOTING THE ISSUE WOULD BE GREATLY APPRECIATED!!!!!

 

Sounds like a hub bearing needs attention/replacement. Any warranty from the dealer you bought it from?

 

+1 on the hub bearing(s). Both fronts on mine were howling when I bought it. I replaced them right away - howling gone. Check Detroit Axle for the best pricing - and buy them in pairs. I installed the Detroit Axle bearings a year ago and have been very happy with them even though they're a third the price of OEM which are ridiculously priced.

 

I have a warranty from Gold Standard; 5 year/100,00 mile that covers just about everything I could ever need, along with roadside assistance. I also have a 30-day warranty from the dealership so I can return the Mini if I’m not completely satisfied. I really like the Mini since I’ve gotten it and wouldn’t like to get rid of the vehicle....

 

So then get it repaired under warranty. Either thru your "Gold Standard" or the dealer.

 

I know a lot of people say check the hub/bearings..check the tire for feathering or alignment wear. I can’t tell you how many MINIs I’ve seen that have cupping or feathering on the rear tires due to bad alignment meant that causes all kinds of noise that sounds like bad bearings.