I posted this this morning in the wrong "Stock Problems" forum so I'm repeating it here for anyone that might have this problem. This bug made the car run like the turbo wasn't even there.

While driving from Tucson to Seattle (via San Francisco and Boise) we had the Check Engine light come on. For a while it was intermittent but then became permanent and the power of the car dropped significantly. We took the car to one of the Bay area Mini dealers and they replaced the air mass sensor on the first trip and reflashed the DME on the second trip. Light stayed on.

When we got to Seattle we took the car to Northwest MINI. They found the same codes as the Bay area MINI dealer (2B5C Air Meter Plausibility, 2B5B Air Meter Plausibility, and 2746 Mixture) but took a different approach to finding the problem. They smoke tested the intake system and found a major leak at the "Throttle Induction T Fitting". They replaced the fitting, cleared the codes, and Chili ***** runs like he is supposed to - fast.

My thanks to the crew at Northwest MINI, they made us happy MINI drivers again.
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Sounds almost exactly like my problem.

I just picked up my MCS from MINI of Concord. They found a broken plastic weld when they smoke tested the intake.

My symptoms were loss of boost and associated engine power, increased turbo spool noise (without modifications to the intake), occasional rough idle, and occasional engine hesitation at low power. I also had a CEL thrown for increased emissions.

I can't remember exactly where the break was, and I left the service paperwork at home, unfortunately. The paperwork also listed the exact diagnostic codes that were thrown, which I believe were similar to yours.

 

In checking my service paperwork, it looks like the car threw a "2B5B - Air Mass Sensor Plausibility" DME fault code.

The problem was "a failed plastic weld at the intake pressure tube that is mounted to the throttle body".

 

 

I believe they were discussing this. Check the applicable intake boot for your model/year. I haven't had this issue but I was just noticing how sketchy the piping joint looked on the corresponding part on my Countryman when changing the air filter.

https://www.ecstuning.com/b-genuine-...t/13717555784/