One problem related to service engine light on has been reported for the 2005 BMW X3. The most recently reported issues are listed below.
The service engine light soon came on. The dealer diagnosed that the following two need replaced 1) valve cover gasket to fix engine oil leak 2) dmtl pump I cannot comprehend these failures from a brand known for quality at such low milegae. Google search shows many Bmws have had these failures but surprisingly there are no recalls.