Without knowing what the DTCs were causing the CEL and what test plan or diagnostic steps the dealership took before you had the pump replaced and what's causing it now, there is no way to offer a guess. The pump could have unmasked other issues, there could have been multiple issues all along, a pump replacement may not have been the best choice given the specific DTC or multiple DTCs. There are thousands of possibilities. The two you mentioned could cause a CEL.

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8/2011 X5 xDrive35d Sport, Black Sapphire Metallic, Black Nevada Leather, Fine Burr Walnut Trim
2/2001 M5, Jet Black, Exclusive Complete Black Walk Nappa Point Heritage Leather, Black Cubic Trim