I bought this 2001 x5 3.0 with the above code showing after several days (or longer) I was basically assuming that this is just a vacuum leak somewhere. Previous owner got tired of dealing with it.

I cleaned the MAF, checked the intake hoses and they're in good shape. I can't actually do a thorough check on CCV since I can't see it well, just tried spraying with carb cleaner around the area for any changes and yield nothing.

I run OBDWiz to check for fuel trims and 02 sensor voltages. The 02 sensor voltages show nothing unusual but the STFT on both banks. STFT1 goes up to 18-20 and slowly dies down when it's warmer to 10 or sometimes 5. STFT2 is within +-5% and sometimes act the same way as STFT1 (at 18-20%) When I rev the RPM to 2500, the STFT on both banks go to 0% but the weird thing is that the LTFT1 and 2 are 0 (always 0) Am not sure if this is an issue with the scanner.

Is it safe to assume that I have a valve cover leak that is small and seals up when warm? Is it normal to have LTFT trims of 0% even when you have a lean code?


when I ran BMW scanner here's the code;
CB [203] Oxygen Sensor Control Bank 2 Control Limit Mixture Limit Rich
CA [202] Oxygen Sensor Control Bank 1 Control Limit Mixture Limit Rich
E3 [227] Oxygen Sensor Controller bank 1, deviation too great deviation rich