I don't think it's isolated to diesels, but I believe diesels may be more prone to this issue due to what Zeta an others mentioned, due to the soot and oil, etc.
I read mini cooper s, e90 M3's, etc..

I finally got the codes again.
p0638 and 4687(Enhanced).
It was under these conditions:
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Make: BMW Model: X5 xDrive35d Year: 2011
VIN:


MIL: On


Diagnostic Trouble Codes

Generic Powertrain

P0638 Throttle Actuator Control Range / Performance (Bank 1)


Freeze Frame for DTC P0638

Calculated Load 82 % Coolant Temperature 183 F

Engine RPM 703 r/min Vehicle Speed 1 MPH

Intake Air Temperature 196 F Air Flow Rate From Mass Air Flow Sensor 1.18 lb/min

Absolute Throttle Position 20 % Absolute Throttle Position E 13 %


Enhanced Powertrain CAN

4687 Unknown Trouble Code Description. Please see your factory service guides for more any information.
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So, not sure what to do next. Go ahead and replace the TB? should I go VDO/Siemens($225), or Genuine BMW oem($399)?
Do you think it's easy to change? 1-10, I think I can manage this as maybe a 5..

Thanks.