P1093 BMW - Root cause or most likely process of elimination

Question

05 BMW X5.
Code P1093.
Have repaired on vacuum leak, and still comes on about 2 hours after clearing.
Any thoughts on root cause? This has been going on for about a month.

Answer 1

P1093 Pre catalytst fuel trim too rich

Clean the MAF (mass airflow) sensor , the enabling crtiteria is when the RPM is from 1800 to 3000 RPM, you will need to replace the front 02 sensor and the rear. As for the root cause the rear 02 sensor reporting a rich running condition.