A little over a year ago, I bought a 2009 Mini Cooper S Base that the seller said was mechanically beyond repair so I got it for $400. I got it to running and driving condition and it has actually been a pretty great little car for me. I do still have an issue with it where it goes into limp mode with the yellow half engine light on the tach and I have low boost pressure. If I clear the codes, I get full boost until the light comes back (usually within the first few big accelerations and going up hills), and then no boost again. The codes it is giving me are P0444 – PCV Circuit open, P2270 – O2 Sensor Stuck Lean, and P0137 – O2 Circuit Low Voltage. The things I have done to the car are: new battery, alternator, PCV Valve, O2 sensors, throttle body, Intake tube from the air box to the turbo, and valve cover vent hose. I can hear a hissing coming from what sounds like the vacuum tank below the intake manifold, but I just tore everything all apart with the intent of replacing the vacuum lines, and nothing was leaking. I am planning to sell the car in the near future and would really like to get it all squared away first. Any thoughts? I have scoured the forums with no luck. I am pretty confident the valve cover was replaced prior to me, and the leak doesn’t seem to be coming from the valve cover. Also, for what its worth, sometimes the half engine light comes on and my cheaper code reader will not read the code, so I think there is probably one more code that I am not getting. Just shy of 184,000 miles on the car, but when its running right it runs great!

 

Also, I failed to mention, I can hear the PCV valve clicking open and closed at idle and speeds up with increased RPM; that is why I originally replaced it thinking it was faulty.